How to style this registration form?

Hi
My current registration form is really plain, and I want to change the style to something else. I have found a css style I want to apply (got the html and css code from cssdeck.com) but cannot figure out how to get the old form to work with the new css style. I have both the new and old form on the same page right now and attached an image so you can see hat I am trying to accomplish.
Thank
[/url][url=https://betflik13.com/jili-slot/][size=1]jili slot ทางเข้า[/size]