From a template you created or cloned from a predesigned template, hover over the image of the template and click SettingsA dialog box will open so that you can edit the name, tags, and category as desired.

If you would like to use a predesigned template, you can either Clone the template to save it under a new name or edit it and click Save As when you are finished editing. You cannot edit a predesigned template and save it under its original name.