How do i create a tab page on facebook where the page is dynamicly generated with a url GET

How do i create a tab page on facebook where the page is dynamicly
generated with a url GET

I have created an app on facebook which uses a page on my website.
The page on my website is generated using a get in the url.
for example https://mypage.com//test.php?k=ccjBGNJSCd
Im having an "intergrate" button which brings up a facebook dialog, like
this:
https://www.facebook.com/dialog/pagetab?app_id=345672345&redirect_uri=https://mypage.com/return.php
But I don't know how to send the get code "ccjBGNJSCd" to the tab page.
I can't put it into the app settings because it needs to be dynamic.