Inline Frames behave like the <iframe> object in HTML. The default page that is loaded into the Inline Frame can be specified by double-clicking the widget in the wireframe.
Additionally, the page in the frame can be changed in an Interaction on the page. In the Interaction Case Properties dialog, click on Open Link(s) in Frame(s). Click Link in Frame in the Actions description to open the Open Link in Frame dialog. Check the option to Open Link in [Label] where [Label] is the label of the frame widget. Then click on Link in the Actions description to select the page to open in the frame.