iCal server sharing?

Firstly, I hope I haven't duplicated anything. I've been scouring the Internet and had no luck finding my answer.

I am a technician in a college (Media Studies department), and we've got a Mac Mini server with Lion which works fine for logging on and file sharing and so on. I also do a bit of teaching in the sense that students book my time so I can show them how to use different software.

What we've had in the past is a peice of paper on the wall for them to do this. But this can be a problem as I am not always available in the room, so they cannot access the booking sheet, or I don't see the bookings they've made.

I was thinking that it would be much better if they could all book time digitally on the computer so that it can be done accross the school and it would be sent back to me to approve/disapprove (the client machines with iCal are all running Lion too btw).

Anyway, I've managed to get it working so that a client, logged on as themselves and iCal set up as themselves with the server address (CalDAV), can add an event to iCal and it then gets sent through to me, which is great.

However, what they can't see is everyone elses appointments which then kinda makes it useless, as I'd have to keep checking to make sure there were no clashes. SO... I was wondering if it would be possible to share the calendar or something. Apple seem to advertise this feature, that multiple users can access the same calendar, but HOW?!

Thanks in advance for any replies!