Modular hangboard construction #1 - plywood board
Modboard #2 - 2x6's
Use a 7/16" wood bit to drill holes throughout the piece of plywood you are going to use for the hangboard surface. The more t-nuts on your board, the more "adjustment" you have for hold positions. You can skip the t-nuts if you are going to use screw-on componants
Hammering t-nuts into the holes is the quickest option. Try to avoid t-nut positons where the board screws onto the mounting 2x4 blocks.
Find exhisting studs above door way and screw 2x4 blocks into the studs with long drywall screws. Finding studs isn't always that easy, tap with a hammer and listen. The others studs should be 16 inches to left or right.
Screw the plywood piece onto the 2x4 blocks with drywall screws
All that's left to do is bolt on some holds (or screw on synrock training pieces)