GD Library?

I’ve recently been switching through themes trying to find a really good one at my new TV site here, but every theme I pick there always seems to be something wrong with it.

The theme I currently have I think there is something wrong with my server and was wondering if I could get some guidance.

Under the Headline and the Featured section I have some pictures that are added in correctly but when you open the picture I get this that shows up in the window instead of the picture

GD Library Error: imagecreatetruecolor does not exist

I’ve tried changing file types for the pictures between .jpg and .png and that does work. So I did a search and got very confused. I was wondering if someone could give me a installing GD Library for dummies kind of tutorial.

I’d appreciate any help. Thanks!