To really learn about PHP you will have to have to use it. So there are a couple of optionshere to consider. One is to get a host that supports PHP where you can upload via FTP the scripts you would like to run (or test). There are some free web hosting sites that do have PHP support dhost.info is one of them. Or you could put a webserver on your local machine and then you can locally test you PHP scripts on it, and when satisfied with them if you do have a www webserver then upload the working script to that server.
Since you are quite new it would be in your best interest to put a server on your local PC. To make life simple you should use a package that will install the webserver and PHP properly for you. There are some great packages such as XAMPP WAMP and MAMP (MAMP is for Mac machines). These programs will properly setup a working Apache webserver the latest version of PHP and MySQL (a database) and in the case of XAMPP Perl (server side scripting language).
A very good introduction online resource for PHP is an online book Practical PHP Programming.
