Throw once with your right hand and catch the rebound with your right hand. Next throw and catch once with your left hand. Continue going up in number of throws and catches, see how far up in numbers you can go until you either miss your throw at the board or if you maybe drop your rebound catch.
Next throw one throw with your right hand and catch with your left hand. Then throw once with your left hand and catch with your right hand. Once again going up in numbers of throws, but this time always throw with your right hand but catch with your left hand. Also throw with your left hand and catch with your right hand. It should look like https://lonemind.com/roche/ this, R/hand throw L/hand catch, L/hand throw R/hand catch, then it gets a bit tricky as you go up in numbers. R/throw L/catch R/throw L/catch, then L/throw R/catch, then L/throw, R/catch. Go up in numbers and challenge yourself, you may wish to play further away from the Nivsta Board to challenge yourself for your game. Play on your own.