You can restore a database backup in PHPMyadmin by doing the following:
1) After entering PHPMyadmin from Cpanel, select the database name that you wish to restore from the dropdown list at the top left of the screen.
2) Select the 'import' tab on the top right of the screen.
3) Push the 'browse' button and locate the file you wish to restore on your local computer hard drive.
4) Click the 'go' button at the bottom right of the screen