I was wondering what I have to add to my HTML webpage so that when people visit my website it prompts them for a user name and password. How do I do this? Thanks!

There isn't really a secure way to make a login via HTML and/or javascript, although I believe that there is a solution at www.dynamicdrive.com using javascript and "fuzzy logic". But, given that the javascript is available for anyone to download, I think that it wouldn't stop anyone determined to break you login. The next step is to using some kind of server side programming: jsp, asp, php, cgi, etc. Your HTML page calls a program on the server that handles the login/password checking and returning the next page. This may not be totally secure either if you are passing the login and password thru normal HTML INPUT fields, because those are sent via clear text thru the internet, so someone who knows how to intercept them can copy and use them. To be really secure, you'd need to either encrypt the login/password before it's sent or use SSL (https).