Purchase dry ice from a local store or an online source. Dry ice is frozen carbon dioxide gas, a substance that goes directly from solid to gas forms without turning into a liquid. Use gloves when handling dry ice, as it is extremely cold and can cause injury when it comes in contact with bare flesh.
Break the dry ice into smaller pieces. Remember to use gloves while doing this, and do this in a plastic bag so you do not lose any pieces. This will allow you to control the size and output of the fog.
Prepare a bucket of warm water. Place the bucket wherever you want the fog to be. If you are using it in a theatrical performance, place the bucket adjacent to the stage to keep it out of sight from the audience.
Drop the dry ice into the water. Clouds of fog should billow up from the bucket.
Direct the fog to a particular area using a fan. If you are using dry ice for a stage performance, have the fan behind the bucket pointed toward the stage. Turn the fan on after you have accumulated some fog above the bucket. You will have to experiment with dispersal rates with your particular fan in order to get the timing right.