You can find a few resources here to help get you going with your wordpress site. Most will be video tutorials, with a few useful webpage links too.

Beginner WordPress Tutorial

How to Upload Images in WordPress

Using the ‘Edit CSS’ tool

(in Appearance menu)
I can’t find a good video tutorial to understand the basics of this function and interface, so here’s the WordPress Support page to give you the heads up on this.
http://en.support.wordpress.com/editing-css/