An app that automatically plans shifts based on the shifts the employees want to (imagine for restaurants)

I started and I’m pretty stuck I do not know how to do that each user enters different shifts.
yes I know about users specific row but still I do not see the shifts
help please

This is not a simple task, i build time clock with shifts planer, weekly paychecks and food calculator for restaurant all in one app

You have to create one sheet for shifts and one for employees time clock, when they clock in, app will relate shift to the time… but in the end it is the time clock in and out what really matters… shifts schedule is just for reminders when to start the work

How to make each employee choose shifts and i want every employee’s choice is saved in my sheet