what code should i use to create a kind of automation that sends 3 emails after 1 day each?
First you should insert the event and the event time to your database.
You should write a scheduled job, that checks the database every 24 hours and sends an email if the current time - the log time > 24 hours.
See:
https://support.wix.com/en/article/corvid-scheduling-recurring-jobs
Thanks