These are the steps I took for this
- Right Click the Hierarchy tab and go to 3D Object. Click on Cube
- Right Click the Hierarchy tab and go to 3D Object. Click on Sphere
- Right Click the Hierarchy tab and go to 3D Object. Click on Terrain
- To change the level design of the terrain, I went to the Inspector tab and clicked the brush on Terrain to form mountains.
- To change the color of the objects, I right clicked the Assets tab and hovered over Create and Clicked on material. I changed the color of the material and dragged it to whichever object I wanted to.
- To change the Skybox, I clicked on Main Camera in the Hierarchy tab, and on the Inspector Tab, it says Clear Flags in the Camera Component. I clicked on Skybox and changed it to solid color.