Change smtp from mail address using c#

Hi,
  i am sending email using gmail smtp credentials. My problem is that, i want to use different email id and username as credentials.

   
 
 
   
    Now i want to show from address ("[email protected]") in client's from address, rather than userName "[email protected]".
   
    Would you please help me to show from address ("[email protected]"), than userName "[email protected]"
   
Thanks