question about web design contest

Sorry guys, I've never send a website graphic design, so I have a lot of question about these particular graphic design contests... I know how to build a graphic for website via PS but.... in some case you have in mind something particular... for example Collins on Pine
how you can send this kind of website to CH?

You create a ps page and explain the effect, because if the final file is only a psd file, I can't understand how the CH can understand what you have in your mind....
someone can explain to me how do in this case?

sorry for my elementary english