Go to Administer » Site building » Modules and click on To Do Views to install the Views extension for the To Do module.
This module requires the installation of the 3rd party Views module.
This page documents the usage of the To Do List module to end users (i.e. not how to install and setup the module, but how to create To Do List items, share them, mark them started/finished, etc.)
For administrative information check out the To Do List module help.