Friends at CPWebHosting please tell me how to launch a webmail for a user?

Well for this you can nevigate with the control pannel.There are icons present int he pannel,use them to reach to the webmail.

There are drop down menus also which contains icons to nevigate,on the header.

from the header.
1)mail info
2)mail manager
3)Type your mail domain
4)Go
5)Click the WebMail icon for the address you wish to view.
6)Click to launch

In this way you can launch a webmail.

Be cautious in writing your mail domain.Espacially if you have many mail domains ensure correct mail domain before typing it.