You will need:
This is as easy as it sounds!
1. Build mounds of dirt forming as many valleys, creeks and spurs as you can. More on landforms
2. Place the sticks upright in the soil where you want your 'trees' to be.
3. Pile leaves and twigs where you would expect them to be on your 'hillside'.
4. Gently pour water over the entire site. Which areas lost more soil... why?
5. What could you do to fix the problems on the site? What if the soil was a different texture?