Summarize this article in one sentence.
Drum keys are used to tune drums and cost about two dollars at a music store. If you're going to play drums, it's a good idea to get one and make sure your kit is in tune with itself. To start tuning your drums or changing the heads, all you need is a stick and your drum key. Turn the snares off and you're ready to start. If you have any drummer friends, you can ask if they have spare keys to lend or give you. Consider using two drum keys at rods opposite each other on the drum. You'll be able to tune faster and will get a more even tension (so long as you continue keeping them across from each other as you move diagonally around the drum). Center the new head on the drum and put the rim and tension rods back onto the drum. You might want to place the rim back on the drum in the spot it was originally since the rim's shape has probably moved to fit in that position. Tighten all of the tension rods evenly using your hands (no drum key yet) and keep going until all of the tension rods are finger tight. Keep your tension rods and drum lugs clean and lubricated. To lubricate the rods, rub a little oil, petroleum jelly, or paraffin wax over them. Prevent your drum from repeatedly going out of tune by pushing down in the center of the drum with your fist. Do this 5-10 times. Don't worry, you won't break it. You should be able to put a good portion of your body weight onto the drum. Don't be alarmed if you hear popping or glue-cracking sounds. Make sure the tension rods are all still tight and adjust them as needed. Once you've got the new head seated and the tension rods relatively tight, you're ready to start tuning the drum.
Get a drum key. Seat the drum head. Break in the drum head.