Find a nice spot in your yard away from overhead obstructions like trees, power lines and decks. Once your spot is chosen you want to dig down roughly 3″-4″ and compact soil as much as possible. Once the ground is level you are able to add 2″ of base stone which will help keep the concrete from having direct contact with with the ground.
Once your stone is added you are now able to set your forms in place. In this case I had some 3/4″ ply wood left over from a different project. The outside dimensions can vary depending on your project and what you have on hand, but in my case I used 3′ outside formwork with a 2.5′ inside form. This form needs to set roughly 1-2″ below ground, we will back fill this to make everything level after the concrete is placed and the forms are stripped.