[Support request] Gateway help?

Hi im really hoping someone with abit of knowledge and maybe experienced this them self knows or can advise more than support.

I have setup a gateway for a competition website which hasnt been easy atall. Finally to the stage where iv been sent the files and added the necessary stuff to the root ect, however iv been sent to hmtl files to edit and return which i really dont understand what would then happen? Would they then send a plugin or something to activate the gateway or would i have to manually do it with the edited html files and put them somewhere? As i say if anyone has made a competition site before you guys will probably know because this gateway is the most common for high risk businesses such as these.

Thanks in advanced i know its a long shot but last resort now im just clueless and everyone seems to have taken their huge chunk of money and left me in the dirt.

cleancompetitions.co.uk – if its relevant