Visit the Official PHP Website
By James N Hitz
Where do I get PHP?
PHP is freeware under the GNU Open Licence Agreement. Both the source code and binaries have been ported to many platforms and are available for download at http://www.php.net. Installation will vary from operating system to operating system. Complete installation procedures are available with your download, or at http://www.php.net. There are several technical, configuration, security and performance considerations that you should especially read carefully.
Please note that PHP will have to be installed and ran at the server. If you do not have access to the server, then you can either download PHP, and then configure a server on your computer, or ask your web-server administrator to install PHP on the server. You CANNOT just copy the .php (or .php3) files to a normal server and hope for miracles! They do not come that easy!