Introduction tutorial?

Now I want to visit the introductory tutorial.
Hmm.. It says here that they want me to learn the very basic about this PHP. It's about creating dynamic webpage (this is only from many functions of PHP).

Before continuing, I would like to know what is Dynamic Webpage?

Here's what I got about it:
 

     "A web document that is created from a database in real-time
       or "on the fly" at the same time it is being viewed, providing
       a continuous flow of new information and giving visitors a
       new experience each time they visit the web site.

       Dynamic web sites offer the user the ability to interact with
       the web site. This interaction can take place in the form of a
       search for products, a questionnaire that automatically posts
       results or online polls. Basically, dynamic web pages and
       content are generated from the input of the user."

reference: http://www.vidoni.com.au/html/glossary.html

From what I understand about this dynamic webpage is, each of dynamic site's visitors will get new surfing experience on the page. Provided they respond to the input's required. So this is like a pre-setup form where visitors will fill in and the content presentation will be presented to them according to the data. But how will they fill in I am still not sure about it.

So before I start learn to write the code, I need to make sure that my server support the PHP file extensions.

How to make sure?
"ask your server administrator to be sure..."