First of all, make sure you’ve set up an actual e-mail mailbox from the Customer Control Panel, and that you’ve waited at least 5 minutes for the changes to take affect.
Then you can either
1) Check your mailbox using the Mr.Host Web Mail Interface @ http://mail.mrhost.ca/
or
2) You can setup your favorite e-mail client to check your account. For instructions on how to setup your e-mail client, consult the e-mail section of this knowledge base.