What is the correct way to turn at speed, say on a 90 degree turn ?

Only way I seem to be able to do it is to hit the rear brake & let the rear wheel skid out a little & then straighten up. I also get my outside pedal down and push down on it & try to lean in.

However, sure I have seen people taking fast 90 degree turns who don't even touch the brakes - how do you do that ? I have tried that and the bike wants to continue going the way it is already going.