To change the name and description on a task you go to the template.
Then open the task by clicking on the task name.
Then from the action menu click on Name & Description.
Now you can change both the name and description of the task and click the Update task button to save the changes.
There is two other ways to access the task edit page.
From the template page open the action bar on the task you want to edit and click on Edit task. This will take you to the edit page.
Another way is to open the task and click on the task name in the header, this will also take you to the edit page for the task.