To login to your webmail, you can go to your website URL and type /webmail at the end of it.
For example: yourdomain.com/webmail
This will take you directly to the webmail where you can enter your email address and password to login.
Please note: If you just signed up and you are using a 3rd party domain that is not pointing to our servers yet, it will need to be pointed to us in order for this to work. You can point your domain to our servers by updating the nameservers to the one's provided in your account information email.