File→ Build Profiles
Add any scenes you want to include in your build in the order they are played→ Open Scenes List
On the left hand side choose what platform you are building for. If you want Mac users to play your game make a mac build, if everyone you know has windows make a windows build, or make both.
If you are selecting a new platform then you have to hit “Switch Platform”
Once your platform has been decided either select “Build” or “Build and Run”
Choose a spot on your computer (not inside your unity project) to place the build, if you know you are making multiple builds its smart to date them
Build just saves it to your computer. Build and Run saves it to your computer and starts the game, it “runs it”
When sharing your build make sure to always zip it first
You will not be able to build your project if you have errors.