Launching your boat will become a simple task with a little practice. However, if you are new to boating you might want to hitch up your boat trailer and head to an empty parking lot to gain some practice. I dont recommend arriving at the boat ramp and attempting to launch your boat before you know how to reverse a trailer.
So, lets look at some of the principles of reversing a trailer
Start with your vehicle and the trailer as straight as possible and about a trailers length from the area into which you want to reverse. Watch the trailer out of the drivers window while reversing slowly, and start turning the steering wheel to the right. Be gentle with the steering it is easier to add more steering than to correct it too much. Some guides to reversing suggest grasping the steering wheel at the very bottom. This should prevent you from over-turning the wheel and if your steering wheel is in a straight position to start with, you will know throughout the reversing maneuver, without having to look, that at the lowest point your steering wheel is again straight.
As soon as the trailer starts to turn you can begin straightening up while still reversing. Dont...