The right pane of the designer is the Detail pane. This is a visual representation of the HTML page, and allows you to add, delete, and modify elements of the page. You can use the Detail pane as you would a form in a standard EXE at Design mode. Double-clicking a control on the Toolbox will add a control to the pane. You can also click a control on the Toolbox, then draw it in the Detail pane. Should you wish to modify any existing elements on the page, you merely click any added controls and resize or delete them like controls on a form.