If you are using Team Foundation Service (i.e. in the cloud, not our on-premise Team Foundation Server), finding the administration pages from the web site can be a bit tricky if you don't know where to look.

Log into your TFS account.  If you don't have one, you can sign up at http://tfs.visualstudio.com.  In the upper-right corner of the page is a gear icon:

Once you click this icon, you will be able to create new projects, manage security, etc.

Thanks to Frank La Vigne for inspiring this post.