How to change forums categories into a custom image
 

I have a PSD file with a bar I want to place instead of the current forum category style.
I have sliced out 2 pieces of it: one is going to be on the right side (RTL forum) set on no-repeat
and the other piece is going to repeat it self with repeat-x

Thing is I don't know how to make this work

Maybe you can guide me :)