1. In Team Explorer right click on the Team Project for which you want to give access rights and select Securiy menu item.
2. In the screen displayed click on the Windows Sharepoint Services Site Administration link.
Note: The credentials of the user doing this changes should have the administrator privilages for sharepoint.
3. Internet explorer will be displayed in which you will be able manage rights for groups and individuals. You also will be add/remove users from a group.