I'll just quickly show how to activate your Sandbox Plugin for GS. This is a really neat little plugin that allows you to do a lot of extra stuff you never thought possible on a basic architecture program. It comes pre installed but needs activation. It will allow you to form contours for many things instantly, without having to draw single lines. It's really great for basic landscaping, but i've used it for Formula 1 car sidepods in the past, so its really very versatile!
Step 1: Step 1
Open a new Sketchup document and go into Window > Preferences.
Step 2: Step 2
When in system preferences, select Extensions. Now tick the Sandbox Tools check-box.
Step 3: Step 3
Now exit the preferences dialogue box and select View > Toolbars > Sandbox
Step 4: Done!
You should now have a sandbox toolbar below your standard top toolbar! You can move this around by dragging it from the handle on the side of the toolbar. I'll put up another instructable on how to use the sandbox plugin most effectively later on! Enjoy! :)