To serve your `index.html` file using Nginx on Arch Linux, you need to follow a few simple steps for installation, configuration, and starting the web server. This guide is meant to help you get started.

### Step 1: Installing Nginx

1. **Open your Terminal.**

2. **Update your system package database** by running:
   ```
   sudo pacman -Syu
   ```
3. **Install Nginx** with the following command:
   ```
   sudo pacman -S nginx
   ```

### Step 2: Configuring Nginx to Serve Your HTML File

1. **Navigate to the Nginx configuration directory:**
   ```
   cd /etc/nginx
   ```

2. The main configuration file is `/etc/nginx/nginx.conf`, but for hosting specific sites, it's a good practice to use the `sites-available` and `sites-enabled` structure, which might not be set up by default on Arch. Let's create those directories:
   ```
   sudo mkdir sites-available
   sudo mkdir sites-enabled
   ```
   
3. Add the following line to the bottom of the `nginx.conf` file to include the `sites-enabled` directory. You can open it with your favorite text editor, for example:
   ```
   sudo nano nginx.conf
   ```
   At the bottom of the file, add:
   ```
   include /etc/nginx/sites-enabled/*;
   ```
   Then save and close the file.

4. **Create a new configuration file** for your site in the `sites-available` directory. Replace `yourdomain.com` with your domain name or `localhost` if you don’t have one:
   ```
   sudo nano sites-available/yourdomain.com
   ```
   
5. Add the following server block (adjust the `server_name` if using a domain, and change `/path/to/your/index.html` to the actual path of your `index.html` file):
   ```nginx
   server {
       listen       80;
       server_name  yourdomain.com; # Or localhost
       location / {
           root   /path/to/your;
           index  index.html;
       }
   }
   ```
   Save and close the file.
   
6. **Create a symbolic link** to enable the site:
   ```
   sudo ln -s /etc/nginx/sites-available/yourdomain.com /etc/nginx/sites-enabled/
   ```
   
### Step 3: Starting Nginx

1. **Start the Nginx service** with the following command:
   ```
   sudo systemctl start nginx
   ```

2. **Enable Nginx to start at boot:**
   ```
   sudo systemctl enable nginx
   ```

### Step 4: Adjusting the Firewall

If you have a firewall enabled (like `ufw` or `firewalld`), you need to allow HTTP traffic:

- For `ufw`:
  ```
  sudo ufw allow 'Nginx Full'
  sudo ufw reload
  ```

- For `firewalld`:
  ```
  sudo firewall-cmd --add-service=http --permanent
  sudo firewall-cmd --reload
  ```

### Step 5: Accessing Your Website

Now, open a browser and go to `http://yourdomain.com` or `http://localhost` if you didn’t set up a domain. You should see your `index.html` page served by Nginx.

### Troubleshooting

- If Nginx fails to start or reload, you can check the error messages with:
  ```
  sudo systemctl status nginx
  ```
  or
  ```
  sudo journalctl -xeu nginx
  ```

- Ensure the `server_name` and the path to your `index.html` are correctly specified in your Nginx site configuration.

Congratulations, you have now set up Nginx to serve your HTML page on Arch Linux!