The toss controls where the ball will go once you hit it. Wherever your tossing shoulder is pointed to is where the ball will end up.
If your serve is going long, you’re most likely tossing the ball behind you. If your serve is going into the net, you’re likely tossing too low.
Don’t stress about your toss, it’ll change each time you serve. The 3 steps will stay the same and help you adapt.