Simply click on the raylib.sublime-project file to open it with Sublime Text. Alternatively you can open Sublime Text first and click on the Project -> Open Project.

It comes with raylib.sublime-build. This file needs to be copied into the sublime packages folder for the user. On windows it can be found in %AppData%\Sublime Text 3\Packages\User.

Once done open the project and select Tools -> Build System -> raylib. To run press Ctrl + Shift + B and select which build you want to run.

For a full overview of build systems please check the build systems guide.