What a great question Samfat!
In order to teach your children how to bring peace to the world, you have to educate them. Teach them the root causes of war, and you're half way there.
Religious and political intolerance are up there on top of the pile, as are greed and extreme nationalism.
Underline the similarities between nations and cultures, rather than the differences, and create a culture of love and acceptance rather than hate and division.
Reduce the massive gap between the poor and the rich nations, give freely, instead of expecting some political return for the assistance rendered.
Create a world democracy.
By the Lord Harry! I sound like an old Hippy! Well...that's because I am.