Individual users can be saved to the administration side of your store under System>Users>Users. Clicking "Insert" will bring you to the user form below. Aside from the basic user information, a password must be created for the user to login to the dashboard. The User Group selected from the drop down box will assign specific permissions to the user. The status lets you choose to enable the user to be able to login, or disable the user from logging in to the dashboard.
The user can access the dashboard the same way the administrator would, with the exception of entering their specific username and password.
Our user, John Doe, was assigned to the Co-worker group; meaning he will be able to access and modify all the Catalog pages. He will not be able to access Extensions, Sales, System, or Reports. The following screenshot displays what John Doe will view when he tries to access the Extensions page.