The URL for your mail client is http://yourdomain.tld/webmail or http://www.yourdomain.tld/webmail
That is for example the name of your domain is http://example.com then the web address for accessing your mail will be http://example.com/webmail.
Managing E-mail accounts
In the Login Screen type your Username and Password in the appropriate field to login to your control panel.
To add email accounts click on the Email icon on the top and than Email mailbox on the left. Thereafter click on the Add new Mailbox button on the right.
Fill in the Form Fields to create new email box or email ID as desired.