With knees bent and back bent to 20 degrees, drop step then turn.
Bounce the ball then chin the ball up to the power box and being square to the board, shoot.
Do twenty of these then move to the other side and do the same thing.
If you are not doing every aspect of the move correctly then do each part of the move more slowly. Form and technique then speed up the move and work on quickness.
Rebounding is the least glamorous thing in basketball and one of the most decisive. It is also almost entirely a habit, which means it is entirely coachable.
Good spacing is only the start. The best modern offences teach players to attack the defence's rotations and play in a permanent 4-on-3 - here is how to coach that read.
The ball screen produces almost half of all professional offensive possessions, yet most teams still teach it as a memorised play. The modern approach trains the read - giving players a framework to decide based on what the defence does, not what the coach called.