In order to backup your Xoops application you have to:
STEP 1 Backup all of your files and folders inside your Xoops installation. You can do that by downloading them via your favorite FTP client. You can find our comprehensive FTP tutorial here.
STEP 2 Backup/Export your database. You can do that by using PHPMyAdmin. Please, check our tutorial on how to backup/restore MySQL database in order to create a backup of your Xoops database.
Please, make sure that you choose the correct database, which your Xoops application uses.
If you are unsure about the Xoops database name, you will be able to find it in the xoops_folder/mainfile.php file. You can view this file through cPanel -> File manager.