WordPress:
If you have paid hosting, you already have WordPress ready to install. You have to log into your account and use the Control Panel (cPanel) to install it. Then you use the Dashboard to edit. If you have a free web site, you need to check if you are allowed to use PHP and a database as these will be needed for a true blog app like WordPress.
Getting Started with WordPress: http://codex.wordpress.org/Getting_Started_with_WordPress#Installation_Troubleshooting_and_Help
Blogging with WordPress: http://www.htmlgoodies.com/beyond/webmaster/projects/article.php/3858226
FAQ Installation: http://codex.wordpress.org/FAQ_Installation
Editing Files: http://codex.wordpress.org/Editing_Files
How to install a WordPress Theme (Video): http://www.thewordpress.com/?p=2259
FAQs: http://faq.wordpress.com/
15 Useful Wordpress Tricks to Make Your Theme Even Better: http://forthelose.org/15-useful-wordpress-tips-to-make-your-theme-even-better
WordPress CSS:
How to Edit a WordPress CSS File: http://www.ehow.com/how_2006995_edit-wordpress-css.html
Custom CSS: http://en.wordpress.com/products/custom-css/
Editing CSS: http://en.support.wordpress.com/editing-css/
WordPress Videos...