This website provides a free and private workbook and methodology for managing Multiple To Do lists. Many people search high and low for that perfect to do list management system, when all they really need is a cloud based spreadsheet and a methodology for managing your lists. If you are moving fast enough, there is no system created by others that can keep up with you properly. If you are moving too fast, you won't use any tools properly.
For clarity, the "To Do's" portion of this worksheet in this workbook has no programming functionality. This is just a methodology.
That said, the Workbook itself is designed with a "NAV1" worksheet as the first worksheet in the workbook. "NAV 1" stands for "Navigation1". Nav1 could also be thought of as a "menu1", "index1". It's just a listing of all the Worksheets in the Workbook. It does not update automatically as the worksheets are added and names are changed, but you can hit a button or select a menu item to update it. This is optional functionality and a good way to learn about the programming infrastructre available in a Google Sheet if yuo haven't learned about it already.