Frustrated

I've tried changing the code for the template on a new blog since I wanted something more unique but I keep getting error messages. I've searched the blog help threads but can't find where the problem is solved. Obviously someone knows how to do it because there are blogs out there with backgrounds that are personalized. Arrgh!!!! Wish I knew what the heck I was doing!!! I'm stopping now, it's just too frustrating...will try it again later.