Custom Pro Site Checkout Page


I need to fully customize the checkout page. This is THE most important page, the one that will convince customers to purchase or make them run out of the site.
I don't understand why I can't find any detailed instructions in the forum support.
The default page is not ok and should be really customized with the rest of the site.
If this is going to require a developer to code all the page then this plugin is missing something in the sense that it doesn't give any chance to present the product in a very attractive matter. Please if you can tell me how? I really spend a lot of time trying to run a super installation with all the plugins and I found myself stuck in the pricing table and page that will give a sense to the whole project.