Framing for a door: Start by driving a concrete forming stake into the ground just to the out side edge of your door frame, which is 2"x4" sides 2"x4" header and 2"x4" threshold. After stakes are in the ground hang your verticals over your gable truss and the stakes. Once both verticals are hung plumb them and drill & anchor your vertical strap and your gable truss to keep it plumb. Then set your level on the header install pipe straps and anchor them as shown in pictures above. See: Truss & verticals