You've made a pretty big mistake. You shouldn't start by asking "what technology would I need..." as that is far too broad a question in almost all cases. You need to understand the core principles first or your efforts will have no basis in real understanding. Once you do, you can then start thinking about specific technologies based on what you understand your needs to be.
That said, I'd recommend looking into the MVC framework to aid your understanding of how this stuff works on a higher level. You need to grasp (or at least have a basic understanding of) the higher-up concepts before delving into the technical side of things. This might help: http://net.tutsplus.com/tutorials/other/mvc-for-noobs/
After you get through that, here is some basic information on the kinds of technology that would have been used to create the sort of game you mention.
The client usually requires the use of the same core technologies.
- HTML for content and structure.
- Static content for non-changing parts of the UI (e.g., the header and footer of each page).
- Dynamic content for changing parts (e.g., if there is a health-bar on the page, this should change to accurately reflect the player's current health).
- CSS for layout.
Something to keep in mind is that the server is what sends information to the client. So everything above will have to be represented in your server-side in some way in order for it to be transmitted to the client.
The server has the job of working with data and presenting that data (via client technologies) to any users in a readable and possibly interactive way. While you are rather limited in your choices for client-side stuff, there are many options to choose from for the server-side.
- Ruby on Rails
- And the list goes on...
Again, it's better to aid your understanding of the higher-up concepts first. I don't know about your classmate but it seems that you yourself have a very poor understanding of what exactly you're getting into. Improve that understanding before jumping into specific technologies.
Hope this helps, I've tried to keep it relatively free of jargon.