A blog consists of org entries. Each entry has a title, some properties and some text. Exporting a blog means publishing all entries with a DONE TODO.

A minimal blog file could be something like:

#+TITLE: Lorem ipsum
#+DESCRIPTION: dolor sit amet
#+DATE:

#+STARTUP: logdone

#+URL: http://blog.example.com

* DONE Lorem ipsum
  CLOSED: [2012-01-07 Sat 00:13]
  :PROPERTIES:
  :tags:     Lorem
  :END:

  Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Donec hendrerit
  tempor tellus. Donec pretium posuere tellus. Proin quam nisl, tincidunt
  et, mattis eget, convallis nec, purus. Cum sociis natoque penatibus et
  magnis dis parturient montes, nascetur ridiculus mus. Nulla posuere. Donec
  vitae dolor. Nullam tristique diam non turpis. Cras placerat accumsan
  nulla. Nullam rutrum. Nam vestibulum accumsan nisl.

Please note the blank line between the properties section and the text itself.

Use #+STARTUP: logdone to automatically add a time stamp when closing an entry.