As others have already stated, yes, you need web server software. If you are only wanting a development and testing environment on your Win98 system, Personal Web Server will meet your needs. It comes bundled with Win98SE (and maybe Win98 -- not SE).
I'm doing some development work in a similar environment, but the site is actually served with apache.
To install PWS, search for "PWS" or "personal web server" in the Windows help.
Good luck.