To create a template go to Page settings → More. Tick the “Make page as template” checkbox. Now, when creating a new page, you will find this template in the “My Templates” tab.
If you are a Business plan subscriber, you can share your templates with other uses. To do this, select the “Allow other users to create pages based on this template by number” checkbox in Site Settings → More. You may then share the template number with another user, who may enter the number at the bottom of the template selection page.
Learn more on creating templates: http://help.tilda.ws/page-template