One more bit of advice. Well, two. Some tires will come out without anything being done to the brakes. The wheel just comes out.

When re-tightening the quick release, I've heard two things. One is that you should need to use the fork for leverage to close it. If you don't, it's not tight enough. The other along the same line is that it should be tight enough to leave an imprint in your hand to close it.

And, if you're doing any riding at all, learn how to do front and rear wheels, and learn how to change a flat so you never have to let a flat ruin a ride.