Simple question

Im sure this question seems primitive to most of you, im new to using foreach with forms my question is how is the best way to keep from getting the submit button from comming through with the variables below is my code. <form method="post" action="?fm=newAdvertiser&a=insert"> <center><pre><b> Advertiser Username <input type="text" name="uName"> Advertiser Password <input type="text" name="pass"> Advertiser Number Of Clicks Or Signups <input type="text" name="numAdds"> Select Advertisement <select name="type"> <option value="1">Paid to click</option> <option value="2">Paid to signup</option> </select> <input type="submit" name="go"> </form> <?php if(isset($_GET['a'])) { $a = $_GET['a']; foreach($_POST as $key => $value) { echo "'$value',<br>"; } } ?> Thanks in addition for any help