Pick a spot in the yard to start a pile or get a compost bin. Then just add organic material - food scraps, paper towels, sawdust, lawn clippings, etc. If you're using a bin toss in a shovelful of topsoil to get started. The topsoil will contain the microbial organisms necessary to break down your material into soil. From there it's pretty self-sustaining. Turning the material periodically will help speed up the breakdown process. Enjoy making your own soil.