Hi Tiffany, I'm sorry to hear that you're having troubles finding the "Iterations" item. My first recommendation would be to check your Layout Template settings, as in New Workfront Experience you are able to customize your Agile team's left panel navigation on Layout Templates - you now have the control over the items and the order that is displaying on your left panel.
I hope this helps! Thanks, Gevorg Gevorg Kazaryan Product Manager