My scenario is to send reports to clients to their personal mail id's like gmail, but how to know the server name and address.
To be able to email the result of your scheduled searches, you need to define your smtp server.
go to the Splunk Manager » System settings » Email alert settings
for the smtp server of gmail, see http://support.google.com/mail/bin/answer.py?hl=en&answer=78775
otherwise you can use any local smtp relay.
Remark, scheduling is an enterprise feature, so it will not work with a free splunk.