Well you need to dissolve it first!
You'll want to get about a cup of water on the stove and add the gelatin to it. Then get it hot but not boiling.
Boiling the gelatin will denature it and it will become useless. Once it's fully dissolved let it sit for 30 minutes to let the gelatin "bloom", then add it to the bottom of a secondary vessel and rack your beer on top of that. The whirlpool action from swirling will ensure it's properly dispersed throughout all of the liquid.