radio button help

[dogmir]

i am trying to create a radio button so that if no is selected they cannot move forward in the shopping cart....and if yes is selected you will be able to.....but i dont know the code involved if no is selected to send them back to the page they are on here is the code i have so far

<input type="radio" value="Yes" name="Radio Button" checked>Yes
       <input type="radio" value="No" name="Radio Button" checked>No
          <?php echo $_POST['Radio Button']; // echo selected radio button value?>

does anybody know how to alter that so it the value for no will not let them move forward? thanks in advance

[dogmir]

does anybody know the answer? i have tried 3 different forums and nobody seems to know or want to help......i plead to the masses.....if you have any insight at all please share it with me thanks