Hi Luke,Layers are not handled through Tabs, but they can be toggled Visible/Hidden using the View submenu under the Tools menu. You can also access layers through the document Properties sheet Layers tab (rightclick anywhere in the drawing window and select Document).
I recommend that you sit in on one of our free webinars; these are a great way to spend 45 minutes or so getting productive with Stardraw AV (or its sibling design applications) and, being live, give you the opportunity to ask any questions you want. You can register at http://www.stardraw.com/company/events
I hope this is helpful