how would I do this in php?

[johnj]

those are the variables that are passed to a php file.
e.g. http://www.abcd.com/test.php?a=1&b=2&c=3

In this case the a,b,c with values 1,2,3 are passed to test.php.

[iam4423]

http://www.w3schools.com/php/php_get.asp
http://php.net/manual/en/reserved.variables.get.php
that should get you started