When you add a new sheet in any presentation, a modal will open up asking you to select the template based on which you want to create the new sheet.
A template is a pre-determined page layout and style, which can be edited to produce the required finished document. A template will indicate where specific page elements are to be inserted and may include standard text or images as required.
The "Choose Template" modal that opens up shows the Infurnia default templates and a "Choose from Catalogue" option as well.
If you want to use the Infurnia default templates, simply click on it and a new sheet with that selected template will be added.
If you want to use templates which are created by your organisation, then go to "Choose from Catalogue" option and the carousal opens up with all the available catalogues. You can select whichever you want by clicking on it and the new sheet will be created.
To understand how to create your own templates, refer to this article below,