Watching the breath meditation
The most popular and recognised form of meditation in Buddhism is "watching the breath".
Watching our own breath, paying attention to it moving in and out of our body allows us to empty our mind of other thoughts. (If thoughts do come and they undoubtedly will) simply notice them and let them go.
It is easy to get trapped into following a thought...you may suddenly remember that you need to buy carrots, this may lead you to start thinking about last time you went shopping and what happened, maybe someone ran into you with their trolley...this may have made you angry and you will begin to dwell on it and remember other times when you have been angry etc etc..., this will lead to a feeling of unhappiness or rage. As you can see by this example it is very easy for your own mind to lead you into bad thoughts and affect the way you think and feel.
Watching the breath helps you to notice the workings of your mind, it gives you a little space in which to be at peace.
To practise this meditation, simply bring your attention to the "in" breath and the "out" breath. Some people find it helps to count the "in" breaths as they happen.. up to ten is a good number. If you suddenly realise that you have become distracted just return to 1 and start again. Some people prefer to count on the "out" breath or simply to focus their attention on the feel of the breath moving in and out of the nostrils. You can try all of these methods and decide which one suits you best.
Whatever you chose, the aim is the same..... just to sit and "be" instead of constantly grasping at the thoughts.
If you don't succeed remember that it takes practice and commitment so just keep going.