This stitch is usually used for hems when the seam should stay unseen.
Step 1: Prepare your Thread
1) Thread your needle. pull the thread through as much as you think you'll need for the length of the seam. A good rule of thumb is double the length, you will have a lot of extra, but that's better than coming up short.
2) Double the thread over at the needle. Cut.
3) Make a knot to secure the two ends.