If your password box and drop down is in a form, then create a hidden field named pageCheck and the value of yes.
Then the user types in the password, selects the drop down, hits submit (use the $_POST method) and the header of the second page has this (psudeo code)
$pageCheck = $_POST['pageCheck'];
IF $pagecheck = "" THEN
<redirect to page 1>
ELSE IF $pagecheck = "Yes" THEN
<page 2 stuff>
ELSE
<redirect to page 1>
END IF
You will need to use a server side language (php/asp) or a javascript to make this work.
Hope it helps,
Johnie Karr