Originally Posted by
Peckish
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.
While technically correct (a 6" square's diagonal is about 8.5"), you need a larger square because of the shapes and seam allowances. Make your square at least 6 5/8" before slicing it. If you want to make it a little larger (6 7/8"-7") you can cut it down after you stitch it. Starch is a great idea, and don't be surprised that adding triangles to a block - and winding up with a square block - is harder than it looks.