About Preloading

I want to preload all the graphics before the page displays (instead of keep loading graphics with slow connection when browsing)

I know something about Edge Preloader and did some research like:

window.AdobeEdge = window.AdobeEdge || {};    window.AdobeEdge.bootstrapLoading = true; 

and  

... AdobeEdge.loadResources();

... AdobeEdge.playWhenReady(); 

But they dont actually load things before display. I know there must be some other codes to load the graphics but i cant find information about this on the internet. Can anybody help? Thanks!