Find a few low hanging bridges, that should give you some mast bending training right quick. :-)
The level of foolishness of just going out and playing around is directly proportional to the size of the boat you're piloting and how much room you have to do it, but given those things, you should be fine. I would recommend you read at least this book: The Complete Sailor
. It's an easy read and it will give you a lot of the basic theory that will make that playing around much more productive.
If you have access to a small sailing dinghy, that would help a lot as well, just to get the idea of changing the shape on a small, easy to maneuver sail.
Finally, look around for nearby sailing clubs. Often the lowest level membership is reasonably affordable and you may be introduced to some experienced sailors who would love to have you out on their boat to show you the ropes, or even better, may join you on your boat for a few hours.