The throttle body actuator is the motor that moves the throttle body blade and is usually integrated into the throttle body itself and not serviceable. If that is the cause of the code, the whole throttle body would have to be replaced.
But that isn't necessarily the cause of the code and the problem you're having, it could be a number of things including damaged wiring. Check out this thread for some tips: http://www.f150forum.com/f4/p2106-please-help-130199/
Search google and read as much as you can about "obd p2106" and maybe throw "ford" in there too and you'll find others asking the same question and hopefully finding an answer.