If this was a really hard bump, it should be checked by a doctor. You could have an internal bleed. This happened to my friend's baby when he bounced himself out of his bouncy seat and hit his head on a ceramic floor. Don't put this off- it can be very serious! Especially if you were hit on any part other than your forehead-(that can withstand a lot more force). In fact, I think you should go to the ER. If your parents aren't home, call and tell them what happened, and don't let your friends leave you alone. You need to be monitored!!
for your headache drink plenty of cold water no juices! no pop! lay down quietly in a dark room with your head elevated and rest ! lack of water in the body will give you a headache if this is not the case see a doctor