WordPress Designer/Developer for Various Projects

Looking for someone that can provide WordPress help as needed. Currently I need someone to help with a background image on the Interphase theme by Elegant Themes ([login to view URL]). The top two colors of the background are a single, repeating image, however my client wants on color on the left, and a different color on the right. Not sure how to make this happen. I have attached a picture to help you see what I'm talking about. Please bid for fixing this only, but I would like to create an ongoing relationship with someone that can consistently help out where and as needed. Thanks!