it's a basic drugs question, not other drugs.
yeah, just put one or two canisters in, most that i've seen hold two.
Add whipping cream, shake, enjoy.
Edit: as with all pressurized gas, be extremely careful in the operation of whipped cream dispensers, chargers, "crackers", and balloons. Pressurized gas is dangerous and can cause cold burns if not allowed to warm up properly.
Worn out threads or a loose fitting on a dispenser or cracker is extremely hazardous as the cartridge can blow out at high pressure, causing severe injury.
Also, clean your dispenser thoroughly on a regular basis as all charger except ISI brand (am I allowed to say that?) tend to leave a black, oily residue.
I won't use any other chargers for baking, so I don't see why you would for recreation, either.