e-mail sending from local host

I am a new drupal user I am in a phase of playing around with it on my computer, I try it how it works.
I can't figure it out how can i send the e-mails. is it possible at all to send e-mails when it is only operating from desktop server?

- i have set up the e-mail at admin -- edit
- and also at config--> site info here i use a gmail account.
-i have internet connection :)
msg i receive after i try to post an e-mail for example from the contact page is:
"Unable to send e-mail. Contact the site administrator if the problem persists."

Please let me know if u have a solution for it

thx