https://www.spalding.com/Possible instructions but registration required to find out if it still exists.http://pfd.cloudz.pw/download?file=spalding+44+77537t+assembly+instructions
www.atlantahoops.com > In-Ground Basketball Goals
The Spalding 88369 NBA Inground Basketball Goal System includes a 60'W x 36'H Pro style extruded aluminum framed Tempered Glass or Acrylic backboard ... Click here to download the Spalding 88369 Basketball Goal Owner's Manual
Dig below frost line, depends upon where you live, but at least two feet deep. I would make the hole about a foot wide. Pole diameter 3-4 inches in diameter.