Hey Will...
From the looks of the tank on your teacher's website, it has been running for a while. It looks like a pretty big tank. Can you tell us how many gallons it holds? I also see another tank in there? Ask your teacher if that is a Quarantine tank. If it is not, keep reading...
You stopped in the right place, and did well with asking for guidance. Speak with your teacher, and see if he can get an additional 20g tank with a small filter on it with only the floss in it (No carbon.) and something from an established tank that has been running and has a good bit of beneficial bacteria on it.
Once you have that tank, add the item from a running tank to it with water from the already running tank in your classroom. Take the two fish you have and put them in the 20g tank, and watch them for a few days. Feed them what the people above have suggested. Once they are eating, it's suggested to treat them with cuppramine if they are showing little white spots on them. Your teacher can order it for you, and help you with following the instructions on it.
Keep the 20g tank, and follow the above advice for every new fish you buy after the 13 weeks is up, and these fish are added to the first tank. This teaches you a Quarantine practice. Skipping this step is one of the biggest mistakes in this hobby.
To help you out more, can you post up some more information? How big is the tank that your teacher brought? This fish gets pretty large, and it may be a good idea to consider trading it in for something that will be more comfortable in the tank if it is not a large tank. What is the other fish that you all purchased?
This hobby is tricky sometimes for older people, so the advice may be a little confusing for you, but if you hang in there, and do it right, you'll be a better fish keeper for it...
Have your teacher sit down with you, and read through the stickies at the 'new to the hobby' forum...
Best of luck, and keep us posted.
Oh yeah: Ask your teacher to post some pictures on this thread about his tanks and setup. He may be able to teach us old-timers a thing, or two...