Guide to download from foo/bar repo.
Download the source code as a zip by clicking the ZIP button in the code tab of https://github.com/foo/bar (note: this will use a lot of bandwidth if you wish to update and is a lot of hassle if you want to make any changes at all, so it's not recommended)
For more info check official Github guide, please.
You can use any Git client to "clone" the repository, downloading a copy to your machine. You can also use Git to "pull", which updates your copy to match recent changes.
$ git clone https://github.com/foo/bar
For more info check official Github guide, please.