Hi, this is how to make a Background online. I hope it helps.. but if you still are having trouble after watching the video send me a message, I can't check all the comments!
Also, once you enter the view mode when you finish - press the 'PrtScn' key and it automatically goes onto your clipboard. You can then take it into Paint, or whatever program you use and cut/crop or do whatever you need with it!
Link: www.wix.com