A template captures an element's structure so you can reuse it: its cards, their size and position, and each field's title and type. The content you've typed into the fields is not included.
Step by step
1. Open an element with the structure you want
Set up the cards and fields the way you like them first.
2. Click Save Template
It's at the top of the element canvas.

3. Fill in the form
Title (required)
Description: what the template is for (optional).
Visibility: Private (only you) or Public (shared in the Template Marketplace). Private is selected by default.
Element Type (required), for example Characters.
Preview Image (optional): a screenshot helps others see what they're getting.

4. Click Save Template
The button becomes available once you've added a title and chosen an element type. Your template is ready to use straight away.
Managing your templates
Your templates, public and private, are in the My Templates tab of the Template Marketplace (click Templates on any element).

Click the pencil (Edit template) to change its title, description, visibility, element type or preview image.
Click the bin to delete a template you made.
To change a template's cards or fields, save a new template from an element with the new structure.
Good to know
Templates hold structure only, never content.
The Element Type is the category a template is listed under when someone filters the Template Marketplace.
Editing a template doesn't change elements it was already applied to.