Okay, here's the Terraform code and explanation, but with a **very important clarification**:

**Terraform cannot *create* a GitHub Organization itself.** The organization entity must already exist in GitHub (created manually via the GitHub website). Terraform's GitHub provider is designed to manage resources *within* an existing organization (like settings, teams, members, repositories, etc.).

Therefore, the Terraform code I can provide will help you **manage the settings** of an organization *after* you have created it manually.

**Steps:**

1.  **Manually Create the Organization:** Go to `https://github.com/organizations/new` (or your GitHub Enterprise equivalent) and create the organization you want to manage.
2.  **Generate a Personal Access Token (PAT):**
    *   Go to your GitHub Settings -> Developer settings -> Personal access tokens -> Tokens (classic).
    *   Generate a new token.
    *   Give it a descriptive name (e.g., `terraform-org-admin`).
    *   Grant it the `admin:org` scope. This is crucial for managing organization settings.
    *   **Copy the token immediately.** You won't be able to see it again.
3.  **Use the Terraform Code Below:**

---

**`main.tf`**

```terraform
terraform {
  required_providers {
    github = {
      source  = "integrations/github"
      version = "~> 6.0" # Use a recent version
    }
  }
}

# --- Variables ---
variable "github_token" {
  type        = string
  description = "GitHub Personal Access Token with admin:org scope."
  sensitive   = true
  # It's strongly recommended to set this via an environment variable (TF_VAR_github_token or GITHUB_TOKEN)
  # or a secrets manager, not directly in a tfvars file unless secured.
}

variable "github_organization_name" {
  type        = string
  description = "The name (login) of the GitHub organization (must be created manually first)."
  # Example: "my-cool-org"
}

variable "billing_email" {
  type        = string
  description = "The billing email address for the organization."
  # Example: "billing@my-cool-org.com"
}

variable "company_name" {
  type        = string
  description = "The display name for the company."
  default     = null # Optional
  # Example: "My Cool Company, Inc."
}

variable "org_description" {
  type        = string
  description = "The description of the organization."
  default     = "Managed by Terraform" # Optional, provide a default or null
}

variable "blog_url" {
  type        = string
  description = "The URL of the organization's blog or website."
  default     = null # Optional
  # Example: "https://blog.my-cool-org.com"
}

variable "members_can_create_repos" {
  type        = bool
  description = "Whether members can create public/private repositories."
  default     = false # Defaulting to a more restrictive setting
}

# --- Provider Configuration ---
provider "github" {
  token = var.github_token
  owner = var.github_organization_name # Specify the organization to manage
  # base_url = "https://github.example.com/api/v3/" # Uncomment for GitHub Enterprise
}

# --- Resource Definition ---
# Manages the settings of an EXISTING organization
resource "github_organization_settings" "org_settings" {
  billing_email              = var.billing_email
  company                    = var.company_name
  blog                       = var.blog_url
  description                = var.org_description
  # twitter_username        = "mycoolorg" # Optional
  # location                = "San Francisco, CA" # Optional
  # has_organization_projects = true # Optional
  # has_repository_projects   = true # Optional

  # --- Member Privileges ---
  members_can_create_repositories           = var.members_can_create_repos
  # members_can_create_public_repositories  = true # Be specific if needed
  # members_can_create_private_repositories = true # Be specific if needed
  # members_can_fork_private_repositories   = false # Optional

  # --- Repository Defaults ---
  # default_repository_permission = "read" # Options: "read", "write", "admin", "none"
  # members_allowed_repository_creation_type = "all" # Options: "all", "private", "none"
}

# --- Outputs (Optional) ---
output "organization_id" {
  description = "The Node ID of the managed GitHub organization."
  value       = github_organization_settings.org_settings.id # This is the Node ID, not the numeric ID
}

output "organization_login" {
  description = "The login name of the managed GitHub organization."
  value       = var.github_organization_name # Directly from input variable
}
```

**`terraform.tfvars.example`** (Do not commit your real token here!)

```hcl
# Rename this file to terraform.tfvars and fill in your values
# Or set environment variables:
# export TF_VAR_github_token="ghp_YOUR_TOKEN_HERE"
# export TF_VAR_github_organization_name="your-newly-created-org"
# export TF_VAR_billing_email="billing@example.com"

# github_token             = "ghp_YOUR_TOKEN_HERE" # Better as ENV VAR
github_organization_name = "your-newly-created-org"
billing_email            = "billing@example.com"
company_name             = "My Awesome Company"
org_description          = "This organization holds awesome projects, managed by Terraform."
blog_url                 = "https://example.com"
members_can_create_repos = false
```

**Explanation:**

1.  **`terraform { ... }`**: Declares the required GitHub provider and pins it to a compatible version range.
2.  **`variable "..." { ... }`**: Defines input variables:
    *   `github_token`: Your PAT (marked `sensitive`). **Best practice:** Set this using the `TF_VAR_github_token` or `GITHUB_TOKEN` environment variable.
    *   `github_organization_name`: The exact login name of the organization you created manually on GitHub.
    *   `billing_email`: Required by the `github_organization_settings` resource.
    *   Other optional variables (`company_name`, `org_description`, etc.) to configure common settings.
3.  **`provider "github" { ... }`**: Configures the GitHub provider.
    *   `token`: Uses the `github_token` variable.
    *   `owner`: **Crucially**, this tells the provider *which* organization context these resources operate within. It must match the organization you created.
    *   `base_url`: Use this only if you are targeting a GitHub Enterprise Server instance.
4.  **`resource "github_organization_settings" "org_settings" { ... }`**: This is the core resource. It *does not create* the org but *configures* the existing one identified by the provider's `owner` setting. It sets various properties based on the input variables. Explore the [Terraform GitHub Provider documentation](https://registry.terraform.io/providers/integrations/github/latest/docs/resources/organization_settings) for all available settings.
5.  **`output "..." { ... }`**: Optionally outputs information about the managed organization.

**How to Use:**

1.  Save the Terraform code as `main.tf`.
2.  Create a file named `terraform.tfvars` (or set environment variables as shown in the example) with your specific values (organization name, billing email, etc.). **Do not commit `terraform.tfvars` if it contains your token!** Use environment variables for the token.
3.  Set the `GITHUB_TOKEN` or `TF_VAR_github_token` environment variable:
    ```bash
    export TF_VAR_github_token="ghp_YOUR_PAT_HERE"
    # Or if using GITHUB_TOKEN (provider default)
    # export GITHUB_TOKEN="ghp_YOUR_PAT_HERE"
    ```
4.  Initialize Terraform:
    ```bash
    terraform init
    ```
5.  Review the planned changes:
    ```bash
    terraform plan -var-file=terraform.tfvars # Omit -var-file if using only ENV VARS
    ```
6.  Apply the changes to configure your organization's settings:
    ```bash
    terraform apply -var-file=terraform.tfvars # Omit -var-file if using only ENV VARS
    ```

Now, Terraform will manage the specified settings for your *existing* GitHub organization.