Yep, now you have your test fodder for stripping paint. You needed one anyway.
I've found plastic water bottles (or pop bottles, I s'pose) are great to practice on. They have many of the shapes you'll find on a typical car body (in some fashion or other), and being clear, it gives you an opportunity to see what's happening with your initial base that may effect later coats.
Main thing is, of course, just keep at it. It's not rocket science, but there is definitely a large "feel" factor to painting, whether it's with a brush, can or airbrush. Once ya catch on to the feel for it, you're 3/4 of the way home. The other 1/4 is Murphy's Law.