In Github you can add collaborators in your project who can work on your project along with you.
Collaborators have the full right to modify your project.
First you need to log in to Github.com.
Then click on the project for which you wish to add collaborators.
Then click on settings.
Then click on Collaborators.
Type the Collaborators’ name you wish to add. Before doing so make sure that the person has a Github Account.
Select and click on Add button to add the collaborator.
You can read : How to add Repository in Github .