change the password through web

hi
I? am using windows 2000 server. It is a file server. I have 100 users. The 100 user want change the password through web access. How to enable the web access to change password in windows 2000. I don?t have a domain controller. All user are attaching the system and they using user name & password than access the folders
so now I want to change the password through the web.