Prefolds are the basic diapers many folks use as burp cloths. They come in different sizes and are thicker in the middle. They can be pinned, Snappied or just trifolded and slapped into a cover (which is what we do most of the time). Prefolds tend to be too long and have to be folded down a bit in the front. I have trimmed mine by cutting a strip off the end and sewing it on sideways in the wet zone. But this is not necessary.

First, assemble your supplies: one cover, one prefold.

Next, fold both sides (the thin parts) over the center (the thick part.)

Lay the trifolded prefold into the diaper cover. Some covers (like the Swaddlebees ABC cover pictured here) have a little flap to tuck the front under, some don't).

Place the child on the diaper and fasten the velcro or snaps (just like you would a disposible).
As my kids would say, "easy peasy lemon squeezie". When the diaper is wet you can just take out the wet prefold and insert another. If the diaper is poopy, replace both the diaper and the cover.
I keep my diapers in the pantry/laundry room in a large rubbermaid tote with a tight lid to contain odors.