Generally people refer to the on-side and off side roll. If you're right handed you normally learn by setting up on the left side and going into the water on that side and going around under the boat and coming up on your right side. That's your strongest bracing side if you're right handed and usually your most comfortable. Your right knee would be for the recovery side (you asked). But it's usually called a hip snap and you use your hips to twist the kayak up as you finish your roll with your thighs locked under the thigh braces. If you start with a lay back style roll, it's less dependent on a hip snap and I believe much easier to learn. The terms don't matter much and people roll with all types of styles. Good luck. Once you get it you'll see it fairly easy. Wear a dive mask so you can see - it helps learning.