Hey!
I've used Aperture for quite some time now and you'll be shocked to learn that there are actually a good amount of tutorials on the Apple site, itself. Give a run through this link:
http://www.apple.com/aperture/how-to/. It's an excellent place to start and the videos are very well done, so it's easy to pick up on what they're speaking about.
Once you get the hang of using the program, I think it's then important to go through each tool and figure out how it works best for your own needs, as no two artists share the same vision.
If there's anything I can help you with, specifically, feel free to ask.