How to modify terrain

Hello everyone,

I have a terrain with contours and i would like to modify it. My problem is that I’m not able to use the sandbox tools (Yes, the extension is activated); also the terrain is not a group. Which is my problem ? Any idea ?
Thanks for your help

Look in the Tutorials category.

There are some tutorials on terrain in there, like:

You can also do a forum search on “Sandbox”:
[url]Search results for 'Sandbox[/url]' - SketchUp Community

Thank You for your help, really