All you have to do is heat up your glue gun with a glitter hot glue stick and fill the candy mold with the hot glue and let the glue thoroughly cool down. Then it can be easily pressed out of the mold and is ready to use.
Information: A shiny mold will result in shiny figures. If your mold is dull, the figures will be dull as well. If you would like these to have more sparkle, you can brush on a thin layer of glue and shake on glitter while the glue is still wet. Then let the glue dry before using.
Another alternative you could di in this case is to shake some glitter into the mold before adding the hot glue. When the figure gets popped out, the glue will be on the front side of it.