autoconfiguration url

in internet explorer or in Mozila fire fox, in the Tools—>option
in menu bar,there will be LAN settings in we have mention th ip address or the proxy server adress manually. Without giving manually the adress, HOW to fill the TAB–> Automatic Proxy Configuration URL. As iam having Linux server and 200 clients in windows Xp.The main thing is that i have to give the browsing facility to all my cliets by selecting this Automatic Proxy Configuration URL in my linux proxy server.This may reduce my manual work of settings to each of my clietnts. pls help me if anybody understand my problem and do the needful..