Just go to http://www.blurb.com/ and it'll walk you through it. Basically, you go to Blurb, download their free uploading software called Booksmart and then it'll prompt you as to whether or not you have a blog you'd like to upload to Booksmart. It'll ask you if you have a blog through Blogger, LiveJournal, WordPress, etc. Once you click on Blogger, it'll ask you for your login information (email address and password). It will then "slurp" your blog into a book format. Some way, some how, the Booksmart program looks through your blog and matches how many pictures and/or how many words each blog entry is and formats it into book form. Then, it's up to you to go through and make sure it's laid out the way you'd like, change fonts and/or colors, add backgrounds, etc. You can really personalize your Blurb book anyway you'd like!
After you've edited the book to your liking, it'll prompt you through how to send it to be printed. (This is all online, you don't have to print it out or take it anywhere. Very similar to ordering photos through Snapfish or Photoworks.) The cost is determined by how many pages your books is. They have categories like 1-50 pages is so much, 51-100 is so much, etc. a 40-page book starts at $12.95. Mine was 96 pages and I got an 8x12 hardcover book with a slipcover and it was $50.