Gee, that's a bit of an ask!
IIS is a commonly targeted product for viruses and needs to be setup properly and updated regularly (as new vulnerabilities are discovered - Microsoft patches) to ensure it is secure. I wold be wary of using this unless you were familiar with the product and comfortable you can keep it secure.
I would give some thought to running something like Apache (WTF - From an MCSE!!) which is more secure out of the box (IMO).
To be honest Charlotte, this is going to take a bit of work and education to get going. There's two parts to this equation.
Infrastructure The website (an intranet is an internal website, not exposed externally - wasn't sure if you are familiar with the term. apologies if I'm telling you to suck eggs) needs to be hosted somewhere. If you have a server in the office it can be as easy as installing Apache or adding the IIS service if you choose that path. You now have the Infrastructure in place to host your website.
Content Now you need to build the website. The actual look and feel of the website itself. You can use all sorts of programs to help you do this. You may even have Frontpage installed on your PC now which will help. There are plenty of free programs to help you do this - try places like
www.download.com or
www.tucows.com and have a look around.
Once you have this content you need to move it into the folder structure on the server so that it can be displayed by your chosen web server (Apache, IIS). You will also need to setup your IIS headers etc.
This is an area which I'm not very strong in, I'm an infrastructure guy, but I think I've got the basics covered. There's lots of information on this Charlotte and it can be a bit daunting to get into it. Domski does this sort of thing in his spare time and is more knowledgable than me so I'd ask him to help you out.
Good luck, you'll be a nerd in no time
[Edited on 10-5-2005 by TP]