You may find crystals which already have a hole in the middle for threading purposes, or you can use crystals which do not have such a hole. First you have to make a knot with the thread. Using the pliers, twist the metal thread so that it loops into the shape of a tear drop, and then use some more thread to loop it around the joint, to fix it in place.
If you have crystals which do not have a threading hole, you use the metal thread to form a casing around the surface of the crystal with the pliers. Don't encase the crystal with the metal.
Just 3 turns around the crystal―the first around the poles, second around the center and third diagonally around the crystal―should do the trick. This takes a bit of practice. If you have a crystal with a hole for threading, then pass the metal thread through the hole and then twist the thread once around either the poles or the center of the crystal bead.
Once the bead has been threaded/encased with the metal thread, then close the knot like before. This time, cut the metal thread with the cutting mechanism of the pliers. With the pliers, ensure that the ends have been firmly fixed and are not protruding. This is to ensure that the pointed ends of the wire do not hurt you when you are wearing the necklace.
With the next bead, pass the loop of the metal through this closing knot, so that the beads are connected to each other. Continue doing this till your necklace is of the desired length. Then with the loop of the last beading, ensure that the tear drop loop of the closing knot passes through the opening knot of the first bead, thus closing the necklace.