I am trying to write some links on a site that would do stuffs for the clients. I kinda want to do something (such as executing a server side script) to a remote client machine (windows machines). Such as downloading something to the client's machine with permission, install vnc for them, etc.

any idea/source where to start? I am ok with html, bash, php/javascript if needed.

To do this with a server side language, like perl or bash, you would be using CGI scripts. These scripts would then do things on the server, so for instance, I have a website that allows me to click a button to start a download on my remote machine, the CGI then executes the following command on the web server:
"ssh user@host command-to-execute-here"

Which then allows the server to remotely control the remote box via the web service.

If you want the browser to take action on the person's machine, you can do that with pretty much any language that supports it, with the most usable being flash or javascript. While I'm not sure exactly how to do what your asking in either, we do have other forums on that.

We can help with a bash CGI script here, but again, that's doing server side processing, not client side, so it wouldn't actually be executing anything on their system unless you have a way to tell their machine to do something remotely such as ssh.

i also want to mention that on my dns server, I went to /var/named directory.. I don't see files like "named.forward" .. does it mean i have to create those zone files?

i figured that name.ca is just a file for cache...