Well, for starters, you might not wanna overuse echo, because (as is the problem in your case) you can very easily make mistakes on quotation marks.
This would fix your problem:
echo "<a href=\"http://www.whatever.com/$param\">Click Here</a>";
but you should really do this
<?php
$param = "test";
?>
<a href="http://www.whatever.com/<?php echo $param; ?>">Click Here</a>