It's time to walk off. But to do that with optimal accuracy, you'll have to do that in a special way as well.
Hold the compass in your hand, with the needle well aligned with the orienting arrow. Then aim, as careful as you can, in the direction the direction of travel-arrow is pointing. Fix your eye on some special feature in the terrain as far as you can see in the direction. Then go there. Be sure as you go that the compass housing doesn't turn.
If you're in a dense forest, you might need to aim several times. Hopefully, you will reach your target B when you do this.
At this time, you may want to go out and do some training, so you could check out some suggested exercises.
Unfortunately, sometimes, for some quite often, it is even more complicated. There is something called magnetic declination. And then, for hiking, you wouldn't use orienteering maps. And this is the issue for lesson 3.