You can begin customizing a template (*.mrep files) once it has been exported from the system and loaded in Report Designer. The editor will display the structure of the template in the Solution window (see figure below), which can be expanded by clicking the arrows () next to each section. The editing area will be empty until a page is selected for editing.
Customizing a template in Report Designer is done progressively as each page of the template is edited separately. In the Solution window, select the page you want to edit (for example, the "Cover" page) and double-click it. It will load in the editing area and you can begin customizing it (see figure below).