To create a news as a template, proceed as usual:
In the app footer, click the big plus sign and then click Write News. Select the recipient(s) and compose the news.
If you want to save this news as a template, click on "Templates" at the top right.
Then select "Create template". The news you previously wrote is now displayed as a draft for a new template.
If desired, you can still edit the template. To save the template, click the "Save template" button.