Go to the View menu and ensure that Layers and Tool are checked. If not, check them now. Select the Elevation layer at the bottom of the Layers window: The Tool window should change if Elevation was not previously selected. It should look like this: At the top is choice of all available terrain brushes. The terrain will be raised up or down in the same shape as the brush. Blue means the terrain will be raised; red means the terrain will be lowered. The other options are: Strength: How much your brush changes at a time.