Hello Ian,
this is little bit tough to explain complete seo over here. I can tell you the basic of SEO. This stands for search engine optimization. In SEO we optimize a website according to search engine to make it rank on the first page of search engines. Because everyone knows more visitors means more business.
Onpage and offpage are the two ways to optimize a website.
Onpage: In this we make the changes on the live webpage. For example: meta title, meta description, meta keywords, heading tags (H1 to H6), Alt tags, sitemap, rss, robots.txt, etc.
Offpage: In offpage we create back-links from different ways like: Article posting, Press release, directory submission, social bookmarking, social media optimization, blog post, blog commenting (many people use but i don't prefer),etc.
To start with SEO following are the steps:
1. Keywords research.
2. Start with onpage optimization
3. create Sitemap.
4. Create RSS.
5. Start with Off page work.
In step 5 i recommend you to start with directory submission and social bookmarking.
For other assistance you can PM me.