Progress Bar in Web Application

Question

Hi,

I need to know how to add a progress bar into a web application. OK, I know how to add it but I can't figure out how to set it up so that it works when the pages load. I've tried searching the net, but i found little pieces of code that i can't understand how to put into my project. Any help? Can someone paste the code below that will give me and understanding of how it works with loading webpages.