Don't get discouraged! When I was just learning, I ricocheted tops off the ceiling, the refrigerator, my dog's water bowl... It gets easier, and eventually becomes more intuitive where you can make adjustments for different tops and string lengths.
The pull back should be a graceful upward arc. I think it was butterfingers who said it was like pulling back a fishing pole.
A whole new world of tricks opens up when you can land a boomerang regularly. Good luck, and keep on spinning!