Drupal is a powerful open source content management system that you can use to manage multiple domains off one Web server. These instructions take you through all the steps to set up as many domains as you need in your Drupal setup.
Here's How:
Follow the instructions to install Drupal on your Web server. Make sure to choose a "multi-domain" setup during the installation process and set up database prefixes.
In the Drupal directory, there is a "sites" folder. In that folder, create a new folder named the same as your second domain. Follow the following structure:
sites/example.com
sites/example.com.directory1
sites/subdomain.example.com"example.com" is your domain and Drupal will administer it, plus "example.com/directory" and "subdomain.example.com".
Copy the settings.php file from the sites/default directory into each domain directory you want Drupal to administer. Then edit that file in each sites/domain directory so that it has the correct database information in it.
In most cases, all you'll need to do is set up a unique prefix for your domain.
If it's not already, point your second domain to the Drupal directory on your server.
Go to the install.php page on your second domain and follow the instructions to install your domain.

