Go to Megaton. Enter Moriarty's Saloon and talk to Mr. Burke. Agree to work with him and he will give you the Fusion Pulse Charge. Go to the bomb in the center of Megaton and activate it (This might be a bug, it does not allow you to activate it yet, so I suggest you get 30 Explosives before doing this.). Rig the bomb to explode or put the Fusion Pulse Charge in the bomb. You are now told to go meet Burke at Tenpenny Tower. Follow the quest marker to Tenpenny Tower and go inside. Sit back, Detonate and enjoy. After the destruction of Megaton, talk to Burke. He will give you the reward and the keys to your suite. Your suite is right next to Tenpenny's room, right of the elevator entrance.
Another way is to let the Ghouls in. Go to the nearby station, talk to the Ghoul you saw talking at the Intercom the first time, agree to help him to take over Tenpenny Tower. Do as you are told in the quest. You should be able to receive the keys to the suite after you are done. (Note: This quest is bugged and may take some time until you can receive your keys, or forever. I suggest you to go through The Power of Atom quest.)
For more info: http://fallout.wikia.com/wiki/Tenpenny_Suite