Saving for Later?

I’m trying to make a building system and a lot of stuff has been successful. One thing that I have been trying is saving. I can’t get it to work. I want to create a button where it saves the thing you built for later. How would you do this?

Short question with no details gets a short answer with no details:

https://www.google.com/search?q=unity+save&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a