Hi BQ,
Thangles are paper patterns to make half-square triangles. Take two different fabrics (whatever colors you want your HST's to be) and place them right sides together. Pin the Thangles paper on top. Set your stitch length to about 1.5, and sew on all the straight lines. After you've sewn on all the straight lines, use your rotary cutter and cut the paper and fabric on all the dotted lines. Remove the paper, finger press open, and you have perfect HST's. You can get a CD with different size HST patterns and print them on your printer.