Passing Querystrings Working Partially?

i'm hoping to have a file 1.php, which takes in a userid via form input, which sends it to file 2.php which shows you available options depending on your userid, and a file 3.php which alters database values depending on your action, and applies it to values corresponding to the userid.

i'm using ajax to request the pages, so they seem to "stack" on the page for the end user

say 1.php

//ajax call up here with a getdocumentbyid to get our 'key' and put it into our get function as a querystring ?key=key in the call for 2.php

<form>
<input type='text' id='key' />
</form>
<div> and 2.php should appear here </div>

[Code]....

so in principle should this work? the last time i pasted all of my scripting here i got zero responses, so i'm trying a different approach this time