i. Create a file called install.site.php where site is the name of your site. This file should be located in the same directory where your install.php file is located (the root directory for your site).

ii. Open the install.site.php file in your favorite file editor.

iii. Enter the following script:

<?php
include_once 'install.php';

$settings = array(
  'parameters' => array(
    'profile' => 'default',
    'locale' => 'en',
  ),
  'forms' => array(
    'install_settings_form' => array(
      'driver' => 'mysql',
      'database' => 'my_db_name',
      'username' => 'my_db_username',
      'password' => 'my_db_password',
    ),
    'install_configure_form' => array(
      'site_name' => 'My site',
      'site_mail' => 'admin@example.com',
      'account' => array(
        'name' => 'admin',
        'mail' => 'admin@example.com',
        'pass' => array(
          'pass1' => 'my_site_password',
          'pass2' => 'my_site_password',
        ),
      ),
      'update_status_module' => array(1 => TRUE),
      'clean_url' => TRUE,
    ),
  ),
);
install_drupal($settings);
?>

This code is used to configure the installation so Drupal knows what values to use during the installation process to properly configure your site as it is created.

iv. Modify the values in the above code snippet to match the needs of the site you want to install. You will need to pay special attention to the database information including the database name, username, and password. You should also modify the administrator's password, site name, and so on to match the desired values for your site.

v. Save the file with all of your changes.