To build the website locally, first install Hugo using your package manager of choice.
For example, on Debian/Ubuntu:
apt-get install hugo
or if you are using Arch Linux:
pacman -S hugo
or using Homebrew on Mac OS:
brew install hugo
Then from the repository's root directory, start the development server:
hugo server --disableFastRender --buildDrafts
Now open http://localhost:1313 in your browser.
...you've got auto-reload powers now. Save a file, page refreshes instantly. So good.