how do i do a backstab

You will need to do some trigonometry calculations to determine your angle relative to the entity you are attacking. You can do this using procedures

This is the equation you use to check the backstab in the "entity is hurt" procedure.
you change the number on the right (45) to change how narrow the backstab range is. 45 will make a 90 degree cone on the back, and 90 will make it 180 degrees ect.