Two seater bench with center table

The armrest and back frame

Fix the backrest uprights [G] to the seat frame as shown in the picture above. Fix them with glue and screws to the seat-frame cross members [B], and the armrest support [E]. Add the backrest frame top-rail [H].
Fix the armrests [F] in place as shown in the picture above. Screw the armrest to the front leg [C], rear leg [D], and the armrest support [E].