Good Morning;
I have used them and had no problems. What is it that you don't understandhow to do? Didn't you get instructions with the package? If not, I will try to help you.
Start by cutting strips of fabric as wide as your Trangles pieces. Take two cut strips of fabric of your choosing and put then together , rightside facing each other. I cut my Fabric the same witch all accross to the fold of the fabric. Then I pin the thangles onto the two strips of fabric. Now you will sew on both sides of the center line in each and every block marked on the thangles. After you have finished all of the sewing, you will cut the blocks apart So that you now have blocks of fabric with the pieces of paper. with two stitched lines on both of a unstitched line. Then you will cut on the line between the two sewing lines. (That was the center line that you didn't sew on at the beganning) .After cutting the thrangles you will now have half triangles. Press open your seams and you will have your finished two pieced block. I hope that was clear enough to be of help to you. Have fun with your THANGLES.
Dick