Place your stone tree surround in place around your tree. At this point, simply lay it on top of the grass.
Cut around the outside of your stone tree surround with your hand shovel. Don't try to remove the grass yet; simply make the cut.
Remove the stone tree surround and set it aside.
Remove the grass from around the tree inside the cut area. In some cases, you may need to use your hand shovel to pry up the grass. Shake excess soil onto the exposed ground.
Set your stone surround in the area where you have removed the grass.
Mulch or plant flowers in the area between the surround and the tree trunk.