When you read books about meditation, or often when meditation is is presented by different groups, much of the emphasis falls on the techniques. In the West, people tend to be very interested in the "technology" of meditation. However, by far the most important feature of meditation is not technique, but the way of being, the spirit, which is callled the "posture", a posture which is not so much physical, but more to do with spirit or attitude.
It is well to recognize that when you start on a meditation practice, you are entering a totally different dimension of reality. Normally in life we put a great deal of effort into achieving things, and there is a lot of struggle involved, whereas meditation is just the opposite, it is a break from how we normally operate.
Meditation is simply a question of being, of melting, like a piece of butter left in the sun. It has nothing to do with whether or not you "know" anything about it, in fact, each time you practice meditation it should be fresh, as if it were happening for the very first time. You just quietly sit, your body still, your speech silent, your mind at ease, and allow thoughts to come and go, without letting them play havoc on you. If you need something to do, then watch the breathing. This is a very simple process. When you are breathing out, know that you are breathing out. When you breath in, know that you are breathing in, without supplying any kind of extra commentary or internalized mental gossip, but just identifying with the breath. That very simple process of mindfulness processes your thoughts and emotions, and then, like an old skin being shed, something is peeled off and freed.
Usually people tend to relax the body by concentrating on different parts. Real relaxation comes when you relax from within, for then everything else will ease itself out quite naturally.