There have been many threads about it: after the slide, slowly push the right stick to the right or left (determines the direction of rotation).
To slow down, reverse the direction or speed, giving small strokes of the right stick in the opposite direction, or agree to the rotation.
There's a lot to learn!
As Marco correctly says the speed can be adjusted by nudges on the aileron. To slow it down or reverse, move the aileron stick momentarily in the opposite direction to flight and to speed it up, nudge the stick in the direction of flight. Max speed is about 17kmh.