Managing Users in Team Foundation Server
You can directly add, modify, and remove users to and from a team project, a team project collection, or Visual Studio Team Foundation Server itself. When managing users, you should determine what the users' roles are and what permissions the users must have to work within the role. Groups in Team Foundation Server have preset permissions, but you must explicitly set permissions for individual user accounts. If you add a user directly to a project, to a collection, or to the server, you must configure at least one permission for that user to change that user's access.
Managing groups is less complex than managing each user individually. Consider adding users to Team Foundation Server groups instead of adding them individually.