The SEOmoz beginner's guide is the perfect place to start. Look up anything you don't understand (backlinks, page rank, domain authority, etc) and don't get frustrated when you mix all of them up and forget half of what you read. It takes time to get it all straight when you're starting from scratch.
My advice is to learn the lingo- there is a lot of it in SEO. Also, start with onpage SEO (it's the easiest to understand). Figure out what makes a page SEO friendly- what google puts weight on as far as the title tag, meta description, h1s, h2s, URL structure, and keyword density throughout all of these components.
However, the majority of SEO (and what google values) is done offpage. This means backlinks, or what pages/domains are linking to you and how they're doing it.
Just remember there's a reason why people get paid a lot of money to do SEO for the big brands. There's a lot to know, and not many people actually know how to do it correctly, but there's also enough people on the internet that even total noobs can make money doing it, so don't give up!