Lay out the slate along the path that you desire to create. Take your time and position the slate in a manner that is aesthetically pleasing. Consider the distance between the pieces of slate as you lay them out and make sure that they are close enough together to comfortably walk from one to the next.
Cut the soil around the perimeter of each slate using a trowel. Lift up each piece of slate and set it to one side of the cut-out perimeter.
With a shovel, dig out the ground from within the cut-out perimeter to the depth of the thickness of each slate.
Set each piece of slate back into its particular dug-out space.
Place a level on each piece of slate and tap it with a mallet until it is level. You may have to lift the slate up and add or remove a small amount of soil to make the slate level.