This is the same way I started designing! My dad would have me design ads for his businesses growing up and I was horrible at first, but as I kept designing the skills started to come. Keep it up :)

Also, Check out Smashing Magazine, http://www.smashingmagazine.com/ it is a great resource for design! and if you get more into web app design 37 signals has an awesome blog called Signal vs Noise. Check it out!