You have tools on your 1, 2, 3 keys with which you can destroy rock s and dirt.
I know, there´s not really a tutorial :) Thanks anyways.
Maybe my comment sounded negative, but I don't think walking simulators are bad! And I knew about the destruction, take Firewatch for example - it's a walking simulator, but you have some other things to do (destruction in your case).
What I want to say, is I actually enjoyed the chilly atmosphere of your game and calling it a walking sim isn't anything you should be upset about!