Nice tutorial! But you can simplify this a lot by using markdown rules instead of html. :) You can search for a quick markdown guide somewhere on the web, but for example it can be something like:

> before text to make a quotation
# before title to make it a headline (## for h2, ### for h3)
*** for new line
etc.

You'll still need center and sub tags. Also, if you want to make an inline image (only half of the width with text wrapping it), you can surround it with div that has a class of "pull-right" or "pull-left".

Try it out and hope it helps! :)