Twitter is a service for friends, family, and co-workers to communicate and stay connected through the exchange of quick, frequent answers to one simple question: What are you doing?
A quote from the author (and he’s not wrong) The class is well documented inline. If you use a decent IDE you’ll see that each method is documented with PHPDoc. There is also a tutorial available here
So, to sum up, these links should kickstart your twittering ability from PHP (and your website).