Adding a domain to Joomla is simple, and can be done in a few simple steps.
1. Open the Joomla Control Panel and click on the Site Manager icon.
2. In the Site Manager window, click on the Domains tab.
3. Click on the Add Domain button.
4. In the Add Domain window, enter the domain name into the Domain Name field.
5. In the Host Name field, enter the IP address or hostname of the domain controller.
6. In the Server Type field, select the type of domain controller from the list.
7. Click on the OK button.
8. Joomla will now contact the domain controller and add the domain to Joomla.
9. Click on the Close button to exit the Site Manager window.
10. In the Site Manager window, click on the Sites tab.
11. Click on the Edit button next to the site for which you want to add the domain.
12. Click on the Domain drop-down list and select the domain that you just added to Joomla.
13. Click on the OK button to save the changes.
14. Congratulations! Your site is now powered by a domain that you own and control!.