Tab templates are references to the files found in /components/com_msrelease/tabs/. These files are the templates that will be loaded in the tabs. To create a new template, just create a new file in the folder. Then just fill the file with what you want to show to your users.
After creating the file, you can create a new tab template in the backend. Select the file you just created and save the tab template. You now have a template which you can re-use for tabs.
Pro tip; check the other files out to learn more about templating.