Running mail example in webapps/examples

How should i edit the conf/server.xml file and change the value for the
mail.smtp.host parameter to the name of a host that provides SMTP service for my network?
Expecting earlier reply.

with a text editor ?

I'm maybe not understanding your real question, but it seems to me you've asked and answered your own question.

For example, if someone asked me how to set up a JNDI mail session, my response would be pretty much your question, minus the first three words.