Then used some blocks and made sure everything was leveled to the way I wanted it. Finally I drilled 3/4" holes through the timber and drove in 2 foot stakes to keep everything in place.
Then filled in the box with soil as well as sloped the sides outside the box.
Then topped it off with a small layer of mulch.
Lastly, stood up the driving range net and tied it down with small rope and screws into the timber. Four!!