PHP and GET/POST

Hi, i got a page that i devided up into 3 diffrent pages, to call i use <form method="post"><input type="hidden" name="step" value="1"> or 2-3, but i found out that you can just write the url: mypage.php?step=1 to get to step one, is there anyway to get rid of that possibility, since you enter diffrent information in each of the pages and submit it, and i dont want people to be able to write everything in the url, like: mypage.php?step=3&name=asj&somethingelse=asd&somethingelse2=asn etc i want everything to be done by POST and if you try to add something to the url like that, then to overwrite it with POST actions or remove that input from the url itself, is this possible? regards Patrick