First you will need to login to the Web Host Manager, Select Software->EasyApache

If your cPanel build is out of date it will prompt you to upgrade. Once up to date select 'Begin Customizing Based on Current Profile'

Proceed through the next several screens until you get to Step 5.

On Step 5 select "Exhaustive Options" and check the option for GD under 'PHP'

Proceed with the Build and Compile process.