I'm new to TFS, and using the 2013 edition. What is meant by iteration path?
I see this when clicking on Work > Backlogs > Backlog and then it allows you to create a new User story or Bug with a dropdown for iteration path.
they're your sprints, you set start and stop dates against them so that you can allocate people to tasks and see how it's all going in your sprint.
The iteration dropdown is meant to be used to further separate your backlog areas into iterations and releases.
See here for more information on Areas and Iterations.