How to Add Background Image into each Blog/Contact page

Hi, I’m using Chocolate. I would like to add a different background image into the blog and contact page. When I upload the image onto the appearance section, it simply use the image for all the pages but I would like separate images please. How can I achieve this please?

Also, I would like to change the mouseover main navigation buttons (left side) to a different font size and color. How can I achieve this too please? Thank you so much!!