Go https://yourdomain.com.au/webmail.

Key in your username and email.

If you haven't used webmail before choose Roundcube as your default.

To login to your website go to http:www.yourdomain.com.au/user

If your menu is no longer displaying just click on the shortcuts link in your navbar and it will reappear. Clicking the Shortcut link toggles the menu on and off.