CSS problem really a server problem, need more help please

[Lynne Puckett]

Hello out there!
Does anybody know how Microsoft IIS works? I wrote previously about how 
only IE was recognizing the CSS on my library's new web page. Mr. Andrew 
Cunningham, to whom profound thanks, taught me about Web-sniffer, which 
says that my page's content-type is coming across as 
"application/octet-stream" instead of "text/css" or whatever the correct 
CSS designator is.
My problem is, I don't know where to look in IIS to find out where to 
correct this.  Web-sniffer says we're using IIS 2.0; the server is WINNT 
4.0 sp6 with the web options pack, which is supposed to be IIS 4.0. I 
don't know what to look for in either version, and would greatly 
appreciate an idiot's guide to changing the content-type in obsolete IIS 
versions. (We're supposed to get a new web server sometime this fiscal 
year, and I get to go to school for it as/when we do. Meantime, I'm 
bone-ignorant, and plenty scared <grin>.)
Any help intensely appreciated.
Lynne