If you know how to close your eyes and breath deep, you know how to meditate already. It doesn't have to be much more complicated than that.
How to meditate? Breath, and watch your breath.
Among the documented benefits of meditation are less anxiety, decreased depression, reduction in irritability and moodiness, better learning ability and memory and greater creativity. That's just for starters. Then there is slower aging (possibly due to higher DHEA levels), feelings of vitality and rejuvenation, less stress (actual lowering of cortisol and lactate levels), rest (lower metabolic and heart rate), lower blood pressure, and higher blood oxygen levels
How to Meditate Right Now
Here's a simple technique that will give you results in minutes. Sit comfortably, close your eyes, and tense up your whole body. Sigh deeply, then breath deeply through your nose and release the tension from every muscle. Just feel each part relaxing, watching for parts that may hold onto tension, like a tight jaw.
If you still have tension somewhere, tense up that part again, then let it relax. It may also help to repeat silently "relax" as the tension drains. This will train your body and mind to recognize relaxation. Later you may be able to relax more easily just by repeating "relax" a few times.
Breath through your nose. This is important because it brings in more oxygen by involving your diaphragm more. You can test this. Breath with your mouth and you'll notice that your breathing is shallower. Then breath through your nose and you'll notice that your abdomen extends more. Air is being drawn deeper into your lungs.
Allow your breathing to fall into a comfortable pattern, and pay attention to it. Pay attention to your breath as it passes in and out of your nose. Your mind may wander endlessly, but all you have to do is continually bring attention back to your breath.
If your mind is still too busy, try naming the distractions as a way of setting them aside. For example, say in your mind, "itchy leg," "worried about work," or "anger," and then immediately return attention to your breathing. Use any way you can to identify and set aside distractions.
That's it. Continue for five or ten minutes, or for 100 breaths. Afterwards, open your eyes and sit there for a few seconds. You'll feel relaxed, and your mind will feel refreshed. And you'll be better prepared for any mental challenges. That's how to meditate.