The Glue is on the flat side of the crystal.
Take a look at the tip of the applicator notice how it is indented to hold the the crystal.
Let the applicator get good and hot.
Pick up the crystal (color side up) just by touching the applicator to the crystal. Thats it! This may take a little practice. Wait about 10 to 30 seconds for the glue to bubbble. It should bubble up pretty good and even turn a whitish color. The hotter the tip is the quicker it will bubble also the bigger size crystals will take longer.
Just touch the crystal down to where you would like it and it will stay! For good! If you are quick about it you can move it. Just touch the applicator tip to the crystal to get it hot again and slide in to the right spot.