Gamma - it does make a difference depending on what program you are using to build your pages. There is a video tutorial on youtube that might help you, but it's for Photoshop Elements. You cn find it here. http://www.youtube.com/watch?v=of3mVxvwtOE
I also know there will be some tutorials that are being created as we speak that will show up here at the Studio not too far down the road as well.