To complete this quest, you must complete 2 specific side quests. In one you must help Dominic. In the other quest, you must help Mike. Dominic's side quest in called "On the Air." Mike's side quest is called "Ashes to Ashes." You can find guides for these 2 side quests here.
Main Story - Black Hawk Down
Main Story - Misery Wagon
Main Story - Only the Strong Survive
Main Story - On the Road