The live Microsoft To-Do tile shows you an overview of recently added tasks. Its possible to add reminders and tasks you need to preform by clicking on the "+" icon on desktop and mobile device.
Clicking on "TO-DO" will automatically redirect you to microsofts To-Do page.

To activate the app:
Change the tile format to 4 x 4 to get live version.
When changed back to 2 x 2 or 1 x 1 format it will show the regular icon.