Hi Marc,
I'll walk you through what I did and hopefully it will help you.
Open up the file named "templates" in the SiteShaper_Shape5_Life_Journey folder. (You will have saved this to a locatable place on your PC/Mac)
There are 3 files related to the background: S5_bg, S5_bg_bottom, S5_bg_top. I copied each one and saved it with the word ORIGINAL in the name to ensure I could go back if I stuffed something up.
Open up each one in Photoshop/PS Elements and you can edit them. Initially I just used 'fill' with the colour I wanted, but then I did a texture on it and I am pleased with the look. (
http://test.gbvic.org) I still have a way to go, but I'm really pleased with the look and it was very simple to do. The S5_bg file is actually a tile, so watch how you change the colour/texture.
Once I was happy with the new colour I saved the file and uploaded it to the site, overwriting the original.
Hope that helps.
Blessings
Jenny