Aside from just saving your template, you can also create a template from the Library.
To create a template from the Library,
1. From the Navigation toolbar, choose Library and select Templates.
2. Click Create New in the top-right corner of the page.
3. From the dropdown menu, select the type of template you would like to create.
4. Choose the template layout you want to use.
5. Select Save as Template to save the template in the Library, otherwise select Create Campaign to create a campaign using that template.