With such a limited amount of information, the information you'll receive will go anywhere from: Convert audio/video to YouTube/Vimeo videos to, use something like slidehsare to provide a powerpoint-like experience. You could easily embed these objects on any webpage.
On the flip side, if you're looking to put these elements in the form of study-guides or tests, you may need PHP, but could also possibly get away with pure HTML pages.
Where PHP, and many other server-side languages, show their power is in dealing with data submitted that holds its state across page loads. You can achieve this same effect with purely javascript implementations; however, they are limited in the amount of data that can be held, and typically what's held in the users session is a limited amount of data; whereas, if you host your own database, you can store much more data without impacting performance.
So your question of moving from a presentation to web-based is very broad. If you give us more details in what you're trying to achieve, other than supporting "i" devices, we could potentially give you a better nudge in the proper direction.