Assuming your computer is on the same network as the othr classroom computers, the address for your server is the IP address for that computer. That address can be found in System Preferences: Networking or in System Preferences: Sharing (they call it Network Address). Under Sharing, it will tell you the IP number and machine name, both which could be used to call up your computer.
If you have Web services turned on you can type in the IP number of your server in another computer in the classroom to see if the sever Web info pops up.