Percentage Preloader with Load Bar by Lostinbeta .....Question?!

I’ve followed the named tutorial, and as it say, it was a simple one to follow. However as a newbie still, and this may sound dumb!! How do I implement the preloader into my website that I have already created?!

My website is pretty much finished but when the external swf’s are loaded it takes a few seconds so i want the preloader to appear on the release of the main navigation buttons? In which case where do I put the code and the graphic?

Please help :puzzled: