I've heard that you can test your php scripts on your own computer, rather than uploading to a web server.
What do I do to get them to work?
Well isn't that a specific question. I suggest you download a) the Apache web server for your platform (http://www.apache.org) b) the PHP engine (for example, http://www.zend.com) c) whatever (if any) database engine you're using.
then install the whole mess and start testing. -L-