In your second photo, sew the pumpkin block to the 'top' triangle, centering the triangle on the block and leaving about 1/4" overhanging on each side of the block. Press and then trim the 'dog ears' off. Do this for all 4 corners. Next, sew the 'side' triangles on to each row. You would line up the 'right angle' part of the triangle with the bottom of the block next to it. Yes, there is extra length on those triangles, but if you always remember to sew the 'square part' of the side triangle even with the base of your blocks you will be fine.