It's servo, not service. But welcome to the hobby. We'll do whatever we can to help you.

You want the servo horn to be as close as possible to 90 degrees to the control surface. Then choose the servo hole that gives you the throw you need at the surface. Closer to the middle is less throw, while farther out is more. It's the opposite at the control surface; closer in gives you more throw and farther out is less. Does the manual tell you what your throw should be?