When Adding Folders to TFS, How Do I Add All Children?

I downloaded the entire source code for Bootstrap to a folder that is managed by a TFS workspace.

I right clicked on the folder (which was colored red), selected "TFS" then "Add", and it added the folder, ignoring all of the contents (subfolders and files alike).

How would I add the folder and all sub folders without going through one-by-one?

Thanks!
nz