you'll want to take that up with your server admin, what your asking to do is create an account on your server's mail server. You dont get rights to that and they may limit how many accounts you can have, call your host up and speak with them.
If your using your own server you made you will have to look for mail server software (theres a bunch out there and some are free most are not).
Once you do this you will need to update your DNS server to point to the address of your server that has the mail server software on it. Configure the server software and your set to go 😃