That's kinda a big question!
An "intranet" is effectively a mini, internal internet for your company, where the web-pages contain company specific information, applications etc.
Another way of describing it would be a bunch of webpages (on one or more servers) that hold company information etc. They are "inside" your company and are, usually, not visible to people outside.
A lot depends on what your company wants on their intranet.
Is it just company info?
Do they want to put up applications?
These can include a company directory/phone book, online purchase requests & forms, HR info etc. The list is literally endless.
You should start by learning about Microsoft's IIS server and Linux web-servers. Which ever you choose will be down to cost (Linux is "free") and personal preference.
There's not much more I can say. Like I said, it's a big generic question. Kinda like me asking "I need to setup a computer network. What do I do?"
You need to do some research and also
clearly define what your management actually want.
Check out the book "The Corporate Intranet - 2nd ed." I haven't read it, but you really need to do some research, and it gets good reviews on Amazon.
http://www.amazon.com/exec/obidos/AS...980350-1852066
This is also a more technical, hands on book you may be interested in.
http://www.amazon.com/exec/obidos/tg...glance&s=books
Good luck, and remember to start at the beginning! Get those requirements and scope down on paper!!
Mr Mephisto