hmm, first take some html lessons, after that buy a php book or browse the internet for documentation and example scripts.
after that u start to play with it.
if u know how to make html pages, the start with php shouldn't be to hard, there are many example scripts on the net.
if u wanna watch php pages on ur own computer u have to install a server (apache e.g) php (handles the server side thingie)
easy install package is phptriad(think it works on most systems, just search for it in google, or look for other php installers)
When u have a server and php setted up, u can watch ur created php pages in ur browser (http://localhost/page) but u need to put ur created pages in the httdocs directory from apache (if u used phptriad).
well.. hope this is something u had in mind... if not be more specific.
