We touched on this several times - the basic skill of steering the dirt bike with the rear brake. While not really approriate for motorcycles in general, this is a basic skill in riding offroad.
Again, the basic idea is that locking the rear wheel will make it loose traction and "come around". We can control this and put it to good use.
The basic movement pattern is
This will cause the wheel to lockup and loose traction. Because the bike is leaned over, the rear will slide and come around. The rate at which the rear comes around depends on many things, including speed and lean angle - these are the ones you control.
You can use this technique to turn and get the bike quickly pointed in the new direction in tight/slow corners. It's also useful in avoiding obstacles/trees etc by changing direction quickly.
The basic mechanism to control the bike during this technique is via lean angle. A big lean angle will cause the rear to come around very quickly.
After initiating the slide, you can bring the bike upright while the rear is coming around, especially if you are in tight trees, without much clearance on the inside of the turn. This will also slow the rate at which the rear comes around, because you used some of the momentum to bring the bike upright.
To stop the rear slide, you quite obviously release the brake and get the wheel spinning again. However, the bike better be upright at this point, otherwise, you need to complement the slide with some throttle.
You need to practice this one as a separate skill.
Start easy, by:
Then get going again and repeat on the other side. You will soon begin to notice how much easier it is to the left, because you don't need that right foot for support, so it can stay on and control the brakes throughout.
Keep experimenting with lean angles: more lean brings it around qicker. If you don't lean the bike at all, you'll see that the rear refuses to come around: the wheel locks but simply follows the front.
Keep experimenting with speed as well. Obviously - don't start fast! Start slow and increase speed as you get comfortable.
The concept of flowing is not just relevant to racing (flowing continuously and keeping the speeds up), but for a much higher level of enjoyment as well. The basic flow here is:
Finally, don't come to a stop every time. You can progress to this: