I have the racquet, but what else do I need? Probably tennis shoes and a bag right? Is there an FAQ of things I need to buy in order to even be ready for my first tennis lesson? Things like wristbands and headbands, etc....
You have the racquet. Next buy some tennis shoes because nobody will allow you to play on a court with black marking sneakers. Shirts/shorts are up to you, just as long as neither are too baggy and loose. If you sweat a lot, get a headband and wristband to wipe the sweat and keep it out of your eyes. You don't need a tennis bag unless you need to carry multiple racquets with you. For the sake of being on the safe side, I'd bring an extra racquet to practice just in case you break a string, and have a back-up racquet ready to use.
A simple backpack is good for carrying little essentials like overgrips, water, and other accessories you might have with you.
If you're a complete newbie, I would recommend picking up some tennis books to learn the basics before starting to play. Otherwise, the only way to get good is to take lessons and practice with players much better than you are.
maybe he can hit a shot and just hasn't gotten lessons yet. he might be a natural like me j/k you don't even really need a bag...just a racquet and some good shoes. Assuming we're allowed to post specific sites, I suggest tenniswarehouse.com if you want to do some browsing/shopping.