Hi,
you can assign your iframe some ids and use that id to access the iframe control and can able to get the elements inside the iframe.
<script type="text/javascript">
function parent_function() {
alert('parent');
}
function doit() {
parent_function();
document.getElementsByTagName('iframe')[0].contentWindow.iframe1_function();
document.getElementsByTagName('iframe')[0].contentWindow.document.getElementsByTagName('iframe')[0].contentWindow.iframe2_function();
}
</script>
This may help you for understanding.
The above mentioned links are also useful. Please go through them.
Thanks