Well, you can either use Javascript to fill in the fields without reloading the page, or you can reload the page and use PHP to populate the values.
Javascript:
<HEAD>
<SCRIPT language="javascript">
function fill_form()
{
document.userform.name.value = 'Rich';
document.userform.date.value = '2/12/01';
}
</SCRIPT>
</HEAD>
<BODY>
<FORM name='userform' action='nextpage.html' method='POST'>
<INPUT type=text name='name'>
<INPUT type=text name='date'>
<INPUT type=submit>
<INPUT type=reset>
</FORM>
<a href='javascript:fill_form()'>Use Default Values</a>
</BODY>
PHP:
<BODY>
<?php
if( $usedefault ) {
$name = 'Rich';
$date = '02/12/01';
}
?>
<FORM name='userform' action='nextpage.html' method='POST'>
<INPUT type=text name='name' value='<?php print $name;?>' >
<INPUT type=text name='date' value='<?php print $date;?>' >
<INPUT type=submit>
<INPUT type=reset>
</FORM>
<a href='<?php print $PHP_SELF?>?usedefault=1'>Use Default Values</a>
<a href='<?php print $PHP_SELF?>?usedefault=0'> Don't Use Default Values</a>
</BODY>
Hope this helps!
-Rich