MongoDB has an integrated user management. This allows you to control access to the databases and to assign read/write permissions.
In Mongo Management Studio you get access to the user management with a click with the right mouse button on a database name in the left navigation tree and by selecting the option "User Management" in the opened context menu". It opens a pop up with a list of existing users of the database with the possibility to edit or delete them. By clicking on the button "Add user" a form for a new user appears. A user is getting a Username and a Password or a Usersource. In the list of the roles you can select the required one and click on the "Save" button to save the user.
A special case is the admin database, which exists in every MongoDB server instance. There are specific roles that are only effective if awarded on the admin database. To get access to the user management of admin database click with the right mouse button on the server connection and select the entry "Usermanagement" in the context menu.
If the server is running in authentication mode and still no global user exists, it comes to a "Auth failed" - error message after adding a user. In this case it must be re-connected just with the stored user data.
The user management refers to the User roles in MongoDB 2.4