Question about workback and this Project with Hard Deadline and Gantt template

A lot of workback questions get answered by pointing to this Project with Hard Deadline and Gantt template. Can anyone explain what I am missing? The first line asks the users to enter deadline as a milestone in the first row, "to create a work-back schedule." But I can't see how this is actually helping with a workback. Even taken as it is found, with the data in the template, the deadline is before any of the tasks.

What am I missing here? And how can I create a workback? I am about to build one from scratch, but I don't want to take them time if there is a head start out there,..