once you got Static IP address, you can make folders in your space that is by default picked up by web clients
in IIS (windows server) that folder is 'wwwroot'
in Apache, it is 'httpdocs' i believe.
so what you do is, make sub folders in these web folders, and asign them u/n p/w etc. and atttach domain settings from them, these can be done via web server softarre settings.
for giving users GUI look, you'll have to nstall some other third party softwares like controlpanel and different names blah blah.