Neither did I, when I started, and I still can't do as much as some of the artists who have participated here. But I taught myself at first because I wanted to make silly graphics of my own cats for my personal amusement (make them sit in pool floaties, put samurai armour on them, etc) and I sort of learned from there. I've never had any real tutelage (oh, except I got a Photoshop Elements for Dummies book for Christmas) but there are lots of great and simple step-by-step tutorials on the internet. I also learned that the slickest graphics don't always win - and I don't always vote for the most technically-advanced picture - there are very often graphics with more heart and more creativity than the ultra-Photoshopped ones. You should try! It'd be fun.
Megan's a great graphics-making colleague but I miss when we had like up to 10 people participating. That was really fun. I hope more people enter again.