80 f-150 ranger throttle cable installation

i just got a 1980 f-150 ranger, and i was wondering how to go about changing the throttle cable. the guy who sold it to me said that is the only thing that needs replaced on it, but i live in nome, alaska and for the condition the truck is already in, it'd be too costly to take it to a garage. does anyone know how to go about this and could give me some directions? thanks.