All great advice above, mind if I jump in? How big is the room exactly? You can screw an outlet adapter right in to that socket. You can get a 4' shoplight fixture at wal mart, home depot, lowes etc. for $8-10, 2 bulbs will cost $6-8 more. Reflector is built in, and IMO they run much cooler than cfl bulbs.
Being new also, I messed around with different pot sizes, and smaller are much easier. I have several plants that were transplanted 3 or 4 times in 30 days to progressively larger pots and they have outgrown the girls that started in big pots. Watering is much easier, most new guys (myself included) tend to overwater, and big pots with seedlings are not very forgiving.
I like wind on my girls, little more than a breeze, 16" oscillators are great, get em' dancing. Wind does alot more than promote stem strength, also improves ventilation, and helps with pest prevention.
Depending on your goals, and how much equipment you intend to add in there, you might want to consider a few other things before buying an HID fixture (yes you need the entire fixture and the bulb). A few flourescents will raise your temp a couple of degrees in there, but an HID with no additional ventilation will turn that into an oven in a matter of minutes. Any of us could help you figure what else you will need to control temps with an HID, but keep in mind you will need something. Not sure how far you want to go with this, but if you wanna keep it simple or cheap, you can go from seed to smoke with flouros, just gonna take some calculations and couple extra weeks flower time.
Good Luck