Hi,
Astano is quite correct with w3schools. They are run by the World Wide Web Consortium, hence W3C, are are the best place to start.
Now, you mention PHP. Without a hosting server you can install a free one called WAMP - Windows Apache MySQL PhP. The version for Linux such as Ubuntu is LAMP, the 'L' is for Linux.
Anyway, once you have installed WAMP you can then write PhP scripts, MySQL databases etc on your own PC therefor enabling you to completely develop your site/application without an internet host - much cheaper.
Your site files are stored locally on your, say, C drive under the 'wamp' folder and accessed in your browser address bar as http://localhost/MYSITE.COM etc.
There is a full tutorial at the WAMP site and lots and lots of help by googling 'wamp'. The latest version is Wampserver 2;
http://www.wampserver.com/en/
Hope this helps and the very best of luck with your studies.