The way to achieve global peace is to create individual peace. The meditation for global peace is a collective meditation. This is a very simple but very powerful meditation. Sit in one circle or concentric circles, holding hands so that you hold the hand of the person on your right with your right hand palm facing down, signifying ‘giving’ peace and bliss, while you offer your left hand palm facing up to ‘receive’ peace and bliss from the person on your left. This connected circle of people generates a powerful energy cycle. The meditative energy of one person is shared by all others. This meditation can be done for at least 21 minutes.
source: Living Enlightenment