The following points may help you:

a. Earth basically comprises of four realms that is Lithosphere which comprises of landforms like mountains, plateaus, plains.
b. We can preserve this realm of earth, by encouraging afforestation, preventing land degradation, preventing over exploitation of resources.
c. Likewise, Hydrosphere consist of water and all its form in the Earth. This realm can be preserved by preventing water pollution, by not dumping industrial waste in the water bodies etc.
d. Atmosphere can be preserved by preventing air pollution, by using smoke stacks, use non conventional sources of energy like solar energy, wind energy,
e. Biosphere  is the place where lithosphere, hydrosphere and atmosphere meet, required for the survival of living organisms. This realm can be prservde by encouraging afforestation, by not killing animals, by maintaining balance of nature, prevent over exploitation of resources.