In order for compost to become rich humus and fertilizer quickly and to achieve temperatures high enough to kill fungus and weed seeds, the materials need frequent infusions of air. Tumblers take most of the work out of turning the pile to accomplish this.
Find a Suitable Container
Get the largest garbage can available, both because you'll make more compost at a time and because the contents can retain heat more effectively. Buy something with a cylindrical shape, which will be easier to roll.
Access and Containment
The lid doesn't have to be tight-fitting, but it does have to hold in the contents during turning. If it won't stay closed under such pressure, use bungee cords or straps.
Without adequate air, anaerobic bacteria produce methane, which doesn't heat up enough to sterilize the compost and could be an explosion risk in a well-sealed container. Drill 1/2-inch holes every six inches or so across the surface of the can, or make several larger holes, fitted with screens to hold in the compost.
Start Up the System
Load a good balance of carbon and nitrogen-rich materials into the can. It's okay to fill it full, as the composting process will shrink the materials to about a fifth of their original volume. Water well as composting bacteria need moisture to survive. Excess water will drain out of the can. When finished, close and secure the lid.
Turning the Compost
To turn the compost, place the garbage can on its side and roll it. Try to do this every day for the first two weeks and at least three times a week for a couple of weeks thereafter. Good compost looks like rich, fertile dirt. If it's also cool, it's ready.