To download a repository hosted on github
[bash]git clone git@github.com:account_name/repo_name.git[/bash]

The git@github.com:account_name/repo_name.git will be shown on the home page for the repository on github.com

To update your code from the master branch of the repo:

[bash]git pull origin master[/bash]

To commit the changes you have made locally:

[bash]git commit -m "the message explaining what these code changes did"[/bash]

To send your changes to the repo at github:
[bash]git push origin master[/bash]