How do I add a Content Template in the Rich-Text Editor?
In addition to selecting a Site Template when you create a new site, you can add a Content Template in the Rich-Text Editor.
Choose how to view the steps.
Video Guide
Step-by-Step Instructions
Select the Templates icon.

The Templates icon looks like a piece of paper with the corner folded down.
Select the Content Template.

Select the desired template. The Site Templates you can select when you create a new site are available among the template options.
Important: By default, the Replace actual contents box is selected. If you have content in the editor that you do not want to delete, uncheck this box.
Add content to the Content Template.

You can now edit the selected template and add your content to it.