Step 3. Fix the "A" frame
When the "A" frame members (two legs and one horizontal brace) are correctly positioned, they can then be secured together.
Use a 100x100 (4x4) nail-on plate
where the two legs join and fix a U-shaped nail-on plate to the top of the "A" frame. See fig.11.
Also see making a U-shaped nail-on plate
Use galvanized bolts to fix the horizontal brace to the legs, one at each meeting.
Hold the horizontal brace to the legs with a couple of clamps prior to drilling the bolt holes.