I know this post is a little late but watch this video...it is really helpful. I was always scared to do any adjustments on my bike for fear of messing it up even more. After watching this video several times I'm no longer worried...at least not as much. I was able to resolve my shifting problem on my own! And that feels so good not having to rely on the LBS all the time.

http://youtube.com/watch?v=D0Xt_QCHD1U