As part of your Agency licence, you can create (or transfer) templates to your Agency Template section. These will then be available to all you clients.
First, just click on your 'Agency templates' section and create a new template
When creating new templates in your Agency Template section, the placeholder template that you see when you 'create new template' is just an inert placeholder - To create an active new template, you just need to click on 'load new template' in the control panel
All the library is in there,
If you wish to create a design of your own within your personal account, or tranfer existing personal templates to your Agency account, just click on 'Save as template' within your campaign builder
Then when you go to create a new Agency template, your custom template will be available in the 'My Templates' option in the menu