Hold the sheet by the two corners of one of the short edges. With the underside facing out, place your hands inside each of the corners.
Bring the corner held by your right hand across to your left hand,and drape that corner over your left hand.
Reach down and pick up the corner that is hanging in front of you and bring it up to your left hand. Then bring the last corner up and fold it over the others. You will now have all four corners in your left hand.
Lay the sheet, which is now folded into a large square, down flat on a table so that all of the corners are in the upper right hand corner as you look down on it.
Fold the sheet in thirds with the side with the corners folding into the middle first and then folding the other side in.
Fold the resulting rectangle horizontally in half. Fold it again if it's not yet the size you want it to be.