We are going to frame out the walk door starting with a piece across the top of the doorway & then a piece down each side using the material we used for the 2” x 6”s . In the future we are actually going to install a door in the opening that will open & close. We want this frame work to be sturdy because we will have pin holes in the top & bottom area for the door to pivot on to open & close.
We are also going to use this same procedure for the garage door because it will have the capabilities of opening & closing. You could install a roll-up door on here if you wanted, (I may address how to make a roll-up garage door in the future) we are going to install a door that swings open & closes like they would have had on an old storage building back in the day.
You want to place your door frame boards even with the high spots on the siding. When you glue them the top board will be even with the siding high spots & attached to the header over the doorway. The sides boards will be even with the high spots in the siding & attached to the 2” x 4”s on the sides of the doorway.
When gluing the trim boards around the walk door you may have to use a little clear tape to hold them in place until the glue sets up. Move on to the garage door & do the same thing with this trim work.