Simplify the following text for a Grade 10 native English-speaking person.
Original: Joshua Treadwell McCown ( born July 4 , 1979 in Jacksonville , Texas ) is an American football quarterback for the Hartford Colonials of the United Football League .
Simplified: Joshua Treadwell McCown ( born July 4 , 1979 in ) is an American football quarterback for the Miami Dolphins of the National Football League .