CSS Change Button Colors Membership 2

Hi there – on the Sign Up page:

http://eatrightpittsburgh.org/register-2/

Can you suggest some CSS to make the button initially green, then a hover effect of background to white, green border, and green text?

Then when you click Sign Up, can you suggest a way to make the Create an Account area less “spread out”, so that the text input fields are next to the guidance text and centered on the page? Can you also suggest CSS to make the same green button for the Register Now button?