You have to decide how strong you want it to be. You basically follow the directions to prepare the jelly as printed on the pack etc, but substitute water with vodka. My normal quantity is the initial water that is boiled should be plain water (vodka will evaporate... duh).
Mix in the jelly crystals. It is important to keep stirring to prevent coagulation at this stage. Then take this mixture off the fire. And pour in vodka. I normally pour in the remaining liquid quantity as vodka, if you want it lighter mix water and vodka. Keep it for setting. After cooled, keep in refrigerator for a while. Either spoon it down your throat between drinks as a chaser. Relish as dessert. Use as toppings on ice cream for dessert. Put a spoon of this stuff in each drink u make as flavored ice. Possibilities are endless.
I prefer setting the jolly vedka in hitkari cups because then its easy to get it out. Tried once to put it in my fancy shaped ice tray but getting it in shape out of the tray was murderous. Now i set it in hitkari pots and it slides out easily when done. Not that shape and size matters when u r downing these shots.