you start at the root directory of www.test.com.

so if this is the url www.test.com/post.php?data=fgfdgfg

you would GET /post.php?data=fgfdgfg

if your url was www.test.com/folder/post.php?data=fgfdgfg

you would need to GET /folder/post.php?data=fgfdgfg