I don't know how I could've been so ignorant of this subject earlier!

It was only a month ago that I started trying to edit a few pics and I also realised that the sigs, tags etc. I see here  are made by the users themselves, not just taken off google:( So I decided to try my own hand at this and I found that I hardly knwo anything about this subject. I've looking for good tutorial ever since. Any good links?