Sending data through post method to an iframe

I have an iframe which is pointing to a moodle site. I need to pass to it my username and password, so that when the iframe is loaded, I am automatically logged in on moodle. So I have something like this: <!-- language: lang-html --> <div id="iframe" style="width:787px; height:700px;"> <iframe id="iframeCon" src ="http://www.somesite.net/moodle/login/index.php" width="100%" height="100%" frameborder="0"> </iframe> </div> My question is how to send my username and password using POST method to this URL?