Grrrrr...Blogger!!!

So I was trying to make my blog look cool with one of those neat templates I see lots of other people using. But no, it just revereted my blog to some default format & took away my layout option so I couldn't even make any changes! I finally got that undone. What am I doing wrong? It seems like the old template is just on top of the new one. How do I make the old one go away without deleting all my links & stuff?