What do you need help with? Adding the triangles? First, I'd square up the block, being careful to leave 1/4" between the points of the star and the edge of the fabric. If you cut a 6" square in half diagonally, the long sides will be 8.5". You can then sew the long edge onto the block. I'd starch the square before cutting diagonally, since you will be working with bias.