I'm not going to give you a long lecture on "how you can save the Earth." But there are many little things you can do… most you probably already know about.

-recycle
-reduce waste
-save electricity (turn off the lights when you don't need them)
-buy some organic foods
-donate to organizations that are doing work to to save Earth, by preserving the rainforests and so on.

And also you could thank God for the beautiful world he made.