On the menu bar click Mail, then Preferences, then Accounts and finally click the plus at the bottom right.

General Information

Account Type: POP or IMAP

Account Description: A personal description for your mail box

Full Name: Your Name

Email Address: The email address you created

Click Continue

Incoming Mail Server

Incoming Mail Server: mail.yourdomain

Username: your email address

Password: mailbox password

Click Continue

Outgoing Mail Server

Outgoing Mail Server: mail.yourdomain

User Authentication - ticked

Username: your email address

Password: your mailbox password

Click Continue

Account Summary

Check your settings

Click Continue if you are happy with them.

Click Done