Question email domain

hi there
let say i bought mydomain.com from namecheap for 9$/year
i learned a little bit about buying a domain warm up it ip, and what i still don't understand is :
how can i creat an email service username@mydomain.com similar to gmail or yahoo.. etc
a page where visitors can open and creat new mail with my domain and start using it as a regular mail.
The simplest way is to subscribe to a hosting service for a few $$$ per month.