Styling Sign-Up Pages

I'm trying to style the payment pages (and other pages) but can't find the css codes to do that. I've attached a screen shot of one of the pages on my site to give you an idea of the elements that I'd like to change. However, I think all I'm looking for initially is the particular css file for this and, second, a description of the codes that affect the title of the page and the various subtitles.

Thanks for your help.

Hi Michael

It is difficult to guide you directly here. Do you have a Skype account ? If you have one, please contact me. My Skype nickname is tuanpnves.

Please talk to me when you are available and I will guide you !

Tuan