In Part 9, first you'll bake the textures for the terrain.
Next, you'll use the Cloner object to clone trees over the terrain. To follow along with this part, you'll need some tree models. You can use your own trees, and/or trees from Cinema 4D's Content Browser.
The trees available in the Content Browser depend on which version of Cinema 4D you are using. A quick way to find trees is to go to the Content Browser and type "tree" into the Search bar (to show the Search bar, click the Magnifying Glass icon). To control where the trees appear, you'll restrict the cloning area to selected polygons on the terrain. To make the tree clones look more varied and to avoid an obvious repeating pattern, you'll use Random Effectors to vary the size and angle of trees.