If you wish to create a task list template from scratch rather than saving an existing task list as a template, you can do that from the task list templates settings.
1. Go to Manage my organization.
2. Select Task list templates in the left navigation panel.
3. Click on New task list template.
4. Enter a name for your task list template and hit Create.
5. Enter a name for the task, add subtasks, watchers, assignees, task duration (days), description and hit Create.
6. You should now see a new task list template with the task you created.