How to create an email ID on the Ubuntu VPS server

I have an Ubuntu VPS server and a website mydomain.com hosted on it in /var/www/html directories and I want to create an email ID something like admin@mydomain.com How should I achieve this? I read many articles on Google and tried some, but it's not working, don't know why.

I need it mainly for to send mails to people via SMTP and if preferable, set it up and use it as if it were a normal mail id like Gmail. Can anybody explain me step by step process to achieve what I want?