Adding a wireless access point to a network?

Almighty forum, I come in need of help!

I'm a student in Sixth Form, and it's my job to organise the theatre tech, and we're trying to get our own wireless network for our kit.

We have a wireless router, (Dlink DI-524, a couple of years old, and all the cables), and I have a basic knowledge of networking, such as DHCP servers and so on, but I don't know how to set it up. We have a working LAN port, so access isn't a problem. And we know the server address. As much as we'd like the IT dept. to do it, or to at least tell us how, they're unbelievably lazy and won't do either.

So, could someone offer some help and instruction for me? If any more info is needed, I'll get it.

Thanks in advance!