This is the full starting application (with image gallery) for the final chapter of Learn Enough JavaScript to Be Dangerous by Michael Hartl, based on the sample application developed in Learn Enough CSS & Layout to Be Dangerous by Lee Donahoe and Michael Hartl.
To get started, first for the repository using the Fork button on the upper-right of the screen.
The next step depends on whether or not you currently have a default GitHub Pages site at <your username>.github.io (as developed in Learn Enough CSS & Layout to Be Dangerous).
If you don't have such a repository, you can clone the gallery app there directly:
$ git clone <clone URL> <your username>.github.io
Then create a new repository of that name at GitHub and push up.
If you already have such a repository, you should clone the gallery app to the default directory:
$ git clone <clone URL>
This will create a local repository called le_js_full, which you can use as a reference for copying over the required files. In particular, you'll need the gallery index.html and the large and small images:
$ cd le_js_full/
$ cp gallery/index.html /path/to/repo/<your username>.github.io/gallery/
$ cp -r images/* /path/to/repo/<your username>.github.io/images/
In either case, you can run the app using the jekyll static site builder:
$ jekyll serve
At that point, the app will be running on localhost:4000. To deploy your app, push up the app to GitHub Pages as described in Learn Enough CSS & Layout to Be Dangerous.