Shamata meditation of the kind that the Zen and Tibetan Buddhists do has been taught for thousands of years and the meditation technique is actually very simple. There is a proper way to sit which I could explain to you, but for now just sit comfortably, pick an object, and focus on it. It could be a pebble, a stick, a spot on the wall -- whatever. Perhaps the most popular object of meditation is the breath, following it in and out as we breathe. Let your mind rest on the object of meditation and do your best not to be distracted. Relax. Just focus on the object. If you get carried away in daydreams or some thought or another, when you become aware this has happened, just drop those thoughts and return to the object of meditation. Keep whatever object you have chosen in mental focus. The secret is that you can’t do it, at least not yet.
You can try, but that is just what it will be, a trial. The more effort you make to keep your focus, the harder it will become. And your efforts to focus are a natural thought generator, like Pandora’s box. There will be a flood of thoughts and chances are you will hitch a ride on more than a few of them. You will forget to remember to focus and wake up some moments or minutes later thinking about what you are going to eat for lunch, that kind of thing. What happened?
Or you will noodle off thinking about all things except what you set out to do, which was to focus on that little stone or stick. If you are honest, you will find that you have little to no control over your mind whatsoever, and trying harder won’t make it so. So what is relaxing about that? Not a damned thing. Rather, it can be frustrating and even downright humiliating. This is why those with a Cheshire Cat smile on their face coming out of their meditation period probably are not doing Shamata but just some kind of relaxation therapy or another, and there are dozens. Awareness meditation being discussed here is actually difficult and anything but relaxing, at least in the beginning.
Of course, making an effort to do regular meditation practice is good. Setting aside some time for meditation each day is good. It’s all good, but the actual meditation process is a lot more like work than relaxing. That is my point and you should know this going in. In general, it is hard to like ‘practice’ of any kind just like it is hard to like working out on a treadmill. We do it not for the returns of the moment but for long-term results. It is the same with meditation practice. The result of meditation practice is a long-term habit of mindfulness, not just on the cushion, but also (and especially) off the cushion in your daily life. The cushion is just your treadmill, your practice area where you work to build a habit.
The above comments are the nuts & bolts of practical meditation, but still just some comments and not the entire instructions. There is a great deal more to understand about posture, not to mention remedies for drowsiness and excitability. Much more. However, basic the technique is very practical and amounts to a mental workout.