Use /gcg to create a server-level group.
To use the /gcg command, you must be a member of the Team Foundation Administrators security group. For more information, see Team Foundation Server Permissions.
Even if you are logged on with administrative credentials, you must open an elevated Command Prompt to perform this function on a server that is running Windows Server 2008. To open an elevated Command Prompt, click Start, right-click Command Prompt, and click Run as Administrator. For more information, see the Microsoft Web site.
Run this command on the local application-tier computer.
Global groups are groups that are created directly on Team Foundation Server. This is in contrast to team project groups, which are associated with a specific project. Global groups can be assigned permissions to perform tasks on the Team Foundation Server itself, such as creating new projects or administrating users.
The following example creates a global group called "cwintst" with the description "Coho Winery Testers."
>TFSSecurity /gcg cwintst "Coho Winery Testers" /server:MyServer