How to get full path of file?

hi, im new and just start learning php. i have a url encoded and not
able to find file path . im able to decode url but not able to find
original location of file . here is url of file http://www.wall321.com/download/file?resolution=1280x1024&file=MTI4MHgxMDI0LzIwMTIwNTI1L3N1bnNldHMgY2xvdWRzIGxhbmRzY2FwZXMgbmF0dXJlIHNreXNjYXBlcyByZWZsZWN0aW9ucyAxMjgweDEwMjQgd2FsbHBhcGVyX3d3dy53YWxsMzIxLmNvbV82OS5qcGc=&name=c3Vuc2V0c19jbG91ZHNfbGFuZHNjYXBlc19uYXR1cmVfc2t5c2NhcGVzX3JlZmxlY3Rpb25zXzEyODB4MTAyNF93YWxscGFwZXI=

hi databhi i think if you need help with php try http://www.w3schools.com/php/php_ref_filesystem.asp