Choose the most level area of your back yard. If the yard is not level, shovel extra snow to the lower areas of your rink to make it as level as possible. Surround the designated area with a PVC pipe border to contain the water that will become your ice. Press the PVC pipe firmly into the snow.
Pack the skating surface snow as much as you can with a piece of plywood. Make the packed snow as hard as you can get it by stepping on the board repeatedly in each area. Use a yard roller if you have one.
Create an ice liner: Lightly sprinkle the packed snow as well as the border, and allow it to freeze overnight. This is to contain the additional water you will need to add to create the skating surface and prevents it from sinking into the snow.
Flood the skating area with water, and allow it to freeze. Fill in any imperfections with watery slush, and allow this to freeze as well.