Customise WHMCS billing to my site

I have a website which is currently being designed, [login to view URL] - I need the billing system WHMCS to be totally customised to my site, so that as my clients pass via the ordering system it completely matches. I think there are only 3 pages that need customising however I have not done this before so YOU must check (google or contact WHMCS) and confirm what work you will need to do. This should be fairly simple so a small budget of $30 is ALL that is available. DO NOT bid more than $30, nor start the project and then say more money.