Changing fonts, sizes

The subscription box is appearing on my home page, but I want to know the css code for

1) Changing the font size, colors, boldness of the labels such as First Name, Last Name, Email.
2) The Subscribe button and the ‘I accept the Privacy Policy text and checkbox’ are totally left aligned. Please let me know the code to bring them both in the center.
3) I also want the code to change the color/font of the Subscribe button.

Thanks