I need a script - checks that backlink has been created before file can be submitted

I created a shareware site at http://www.easysoftwaredownloadsite.com. My submission page currently only requires that a url of the shareware file be submitted. I need a script that also requires them to enter a backlink to my site, requires them to enter the exact url where they put the backlink to my site, and that checks that the banklink is there before allowing them to submit by pressing the submit button. Can anyone show me such a script or write me one? I based my website on PADkit.

 

all is well that ends well. project completed