Special thanks to SEO Book for posting a link to the Yahoo! Search Marketing Workbook. This is the 101 page document supplied by Yahoo! Search Marketing (formerly Overture and GoTo.com before that) that gives you all of the direct instructions on how to purchase, write, bid on, track and manage words on their pay-per-click system.
Obviously, beyond the Yahoo! Search Marketing Workbook, there are countless tools, tips, tricks and tactics to learn how to better leverage your organic and paid search results, but this is a great start.
What I like about the Yahoo! Search Marketing Workbook is that Yahoo! does break it down and simplifies the process. All too often, I find that search engine optimization and marketing firms try and make people think it's more complicated than it is. I'm not saying it is not complicated and does deserve a lot of attention, but it's also perfectly fine to buy some words, write some text ads and test it out for the fun of it.
You can get the PDF here: Yahoo! Search Marketing Workbook.