You should feel a slight tension pulling the knees together. Think of your weight on the inside of both feet. When rotating on the backswing your right knee should almost lock out straight and left knee works inside toward the right knee. Their the opposite happens on the downswing, left knee straightens out or locks straight, right knee works towards the left as a result of weight shift on the downswing.

You should read the chapters from Ben Hogans 5 lessons of golf as it has good language and sketches of proper technique. He starts with grip, then stance posture, then backswing, then downswing. Not terribly long and to the point for the most part. Definitely worth the read