The following steps will show you how to login to webmail.
Visit yourwebsite.com/webmail
Enter your username and password, and then click OK. (Note: Username is your complete email like: name@yourwebsite.com)
You should now be logged in, Click on one of the three webmail clients (SquirrelMail, Horder, or Roundcube) to start using your email.
You can now send me a test email :)