Yes, StormForum is kinda right, but there is nothing wrong if you want to get your feet wet with some scripting. But after you've read those ".. for 24 hours" thingies!
hey if your still looking into learning php i suggest watching these video tutorials, they are very easy to follow and i've learned a good bit from it. http://www.phpvideotutorials.com/
Whenever this question comes up, I generally suggest Build your own Database Driven Website using PHP and MySQL by Kevin Yank. (Sitepoint.com) But I also suggest w3schools and forums like the one you're on now and phpfreaks and www.webdeveloper.com
http://w3schools.com has tutorials on every web language there is But yeah, Learn HTML as full as you can, for a full PHP website you need HTML CSS and PHP at least (i'm a PHP noob, i ony understand how PHP/CSS work, i can only code in html)
I'm not a programmer, but I learned everything just by pulling apart Wordpress. Now I can code & design my own themes from scratch. I can't "SEE" code like a programmer should, but I know what to do to get things right. Now, I build custom websites in Wordpress from scratch & they are really good.
First of all, good luck to all who wants to learn HTML/CSS/PHP. Then to my main "gripe" about this. "Everyone" wants to learn to make "cool websites". What we end up with is usually garbage, and an enormous amount of webpages which doesn't bring any real value to the plethora of webpages already available. My best tip would be "find out what you want to do", then procure the skillset for doing just that. There are so many good frameworks and template-engines readily available, so if you're gonna make something "simple", like a blog, a web gallery, a news-site, a social-networking site etc., you could probably do a lot worse than just learning how to use the tools readily available. As for the "Learn <whatever> in 24 hours", I find those books mostly to be a joke. They usually have the basics down, and they offer some good examples, but they rarely touches the basics of coding - security, knowing why and what you are doing, and simplicity as a rule of thumb, to make further updates easier. Good coding practices is even more important on the web, as there are thousands of possible exploits. Start by learning basic HTML. Then move on to learn CSS properly. There is so much bad HTML and use of CSS out there, it hurts my eyes. For a W3-fanatic, where everything MUST validate, it's troublesome to see sloppy coding and bad practices, and semantically wrong coding. Then you might move on to PHP, although I would maybe suggest also learning javascript, especially a javascript library as jQuery or Mootools. You can do lots of "cool stuff" using HTML, CSS and PHP, but you won't be able to go the "extra step" before you can and do use some javascript for effects, interactivity and general usefulness of the page.
I suggest learning from http://www.w3schools.com It has lots of examples, and it's a good site for references. Though php.net has better references.
In the years since I posted the above, I have learned that w3schools is not a reliable source because of blatant security flaws in their sample code. The other sites I mentioned should still be good references. I'd now add stackoverflow.com and the stackexchange family of sites.