Texas has a very active sailing community. I'd bet you can grab some time on someone else's boat without too much effort. That's a great way to get a feel for what to do.
Now, don't get me wrong - I'm not saying that you shouldn't go out on your boat until you've done the above. I'm all for "hands-on" playing, and even failing (I've done/do my fair share of it!). But that's not always the most efficient way to learn, especially with your (now slightly distrustful) wife watching (not that I'VE ever been in that situation
Regarding your question about sail trim, that's the key to the whole game here. If you let the sail out too far, it will flog/flap around, and the sail can't create an efficient airfoil. To oversimplify, you can imagine that you're creating "bumps" in the air that reduce the forward motion of the boat. Sheeting the sail in too tight will cause inefficiencies too, and will tend to make the boat heel (lean) because of the forces the wind is exerting. Too much heel, and the boat goes over. It doesn't happen as often when under a headsail alone, but...
Also, remember that while your goal when out "playing" may be to make the boat go as fast as it can (or at least as fast as you are comfortable), when it's time to come home, your goal is to sail back to the dock. The sail trim for those two purposes will likely be very different, and the boat likely won't move anywhere near as fast on the way home as it did when you were out playing. That's both OK and normal.
When we took our lessons my wife and I went out with the old sailor, rather than the young kid instructor, because the kid was more interested in going fast. I told our instructor that I wanted to focus on learning how to sail to a point - speed meant nothing to me if I couldn't get back to the dock.
You might want to consider picking up Sailing for Dummies or another such book, and you should check out the Articles section here on Sailnet, too. There's a lot of good information there.
Most importantly, don't give up, and keep coming back and asking questions. The folks here are very patient (well, most of them), and are great sources of information.