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.