The most commonly used method for meditation is to sit on the floor with your legs crossed (or sit in a chair, or lay down, depending on what is comfortable), and then quiet yourself and remain there. This will feel incredibly unnatural at first. You will likely experience an urge to move around, to scratch, or to get up and do something. You may even experience some anxiety. This is okay. The nature of the task is to simply observe these urges and sensations as they occur, and then to let them go when they are no longer urgent. Don't act on these urges, but instead simply observe them. A variety of thoughts and feelings will parade through your mind making their usual demands; your task is to observe them rather than to respond to them. Hold on to nothing; just watch. If you get distracted and start acting on an urge, just note that this occurred and go back to your watching. Sit there and observe for 5 minutes (set a timer so you don't have to watch the clock - which will kill the experience). When the timer goes off, get up and go about your business.
Meditation is not something that will pay off quickly. In fact, it will take quite a long time of regular practice before you will "get it" and start feeling the benefits it has to offer. Practice meditating every day at a regular time, for a regular duration. Remain alert during your practice; do not go to sleep! Be patient. Ultimately, your perspective will start to evolve and you will grow more able to choose your moods and reactions instead of them choosing you. Meditation practitioners typically report feeling much calmer than they did prior to meditation, and much more focused and clear-minded.