adjusting the truss rod does not adjust the action of the guitar. adjusting the truss rod changes the bow of the neck and should only realy be done by someone with experiance or a tech.
Adjusting the truss rode corectly will eliminate or reduce any fret buzz if the guitar is set up with a low action.

generally as suicidalmoose said the action is adjusted with the sadles at the bridge, where the strings enter the guitar.