Subscribe by email plugin. How to change style?

Hey guys,

Plugin seems to work lovely, but the style is not so lovely! The plugin is here:

I'm no CSS pro so wondered what code i can add to my custom css to make the email text box the full width of the sidebar, add an image above the text "Completely spam free, opt out any time. We'll email you each time we publish a blog post." and also add a background colour and change body text?

You can flick me the CSS and i'll tae it from there!