It depends too much on what that code is made to do.
If the code targets Web application, you need to create some Web application using the code and deploy it on some server using some Web hosting which supports PHP.
It can be a stand-along PHP application. To run it, you need to install PHP:
http://www.php.net/[
^].
Now, let's come back to the Web application. Alternatively, you can host and run a Web application with PHP on your local computer. The easiest way to do this is this: 1) install PHP; 2) install Apache HTTP server; 3) install the Apache "module" mod_php on your Apache server and configure it to use PHP installed on the first step. Normally, mod_php is a standard option included in Apache installation.
See:
http://en.wikipedia.org/wiki/Apache_HTTP_Server[
^],
http://httpd.apache.org/[
^]
One remote alternative is this: you can run and debug (some) PHP codes in .NET and/ore ASP.NET Web site. The easiest way to do it is Microsoft Visual Studio which already provides a development HTTP server which is ASP.NET enabled and configured properly. On top of that, you need to install Phalanger and Plalanger Visual Studio integration add-on.
See:
http://en.wikipedia.org/wiki/Phalanger_%28compiler%29[
^],
http://www.php-compiler.net/[
^].
—SA