Every installation of Microsoft's Exchange Server is a custom installation. Only someone on your firm's IT staff can help you if you have trouble. Your server administrator does not have clue. This is not unusual.
There is something that you can do to help yourself. Find a Windows machine that uses Outlook to access your Exchange server. Go through its settings and write them down.
On your Mac, launch Mail and then use its Exchange setup wizard to try to enter those settings. This is not guaranteed to work. If it doesn't work, then you may try to setup your Exchange account as an IMAP account, which may or may not work. Failing to setup your account in Mail, then you may try it in Microsoft's Entourage 2004 or Entourage 2008.
Personal Experience: My firm uses Exchange. When I first upgraded to MacOS X, I was able to setup my account in Mail using its Exchange settings. It was far better than Entourage 2004. Unfortunately, my firm "upgraded" its server a few months later. The "upgrade" disabled Mail. Now, I must use Entourage 2004 or Entourage 2008. Under MacOS 9, Outlook 2001 works like a charm--an old charm with chipped paint.