Dissection of a WordPress theme walks you through the default, step by step by step, available in Part 1 and Part 2. I hope the everyone writing these great guides considers moving them to the Codex at some point so they can live on as lasting and shared resource for the community..
Yes it’s a great guide, and thanks to John we have already translated the first 2 parts for the italian wiki, if John will put them on the codex would be great.