You'll need Xcode to be able to open the files contained within this repository. You can find Xcode in the Mac App Store. You can also find it at the Apple developer portal, but if you have access to that you probably already have Xcode, right?
If you've never used git before or don't really have a great familiarity with it, you can grab these files by downloading the .zip archive.
Basic notes about Swift to prep for making a simple iOS app.