If you ever plan to take on investment or bring on co-founders, employees, advisors, consultants or partners and you want to share equity with any of these stakeholders, you need to have a capitalization schedule.
The cap schedule helps you plan out how the equity in your company gets distributed, to whom, when and at what valuation. It is not something you can take to the bank now, and whatever you come up with now will surely change, but you want to think about it now so that you can plan your valuation properly.
Please read the notes I have embedded in cells so you learn how to use it.