Once you've chosen your page size and clicked "OK" then you are presented with a fresh blank page. You can now begin to layout your images and panels that will hold the images and speech balloons first and add images afterward. The easiest way to layout the panels on a page is to drag a page template from the browser and drop it on the page. The cells from the template are automatically scaled to fit the page.
As pages are created in the comic page icons are also created in the page organizer to the left of the main editing area. Click on the icons to quickly select a particular page. You can also drag these icons to reorganize the pages.