I am not really sure how to start with this so any help would be really appreciated.
The full description from Google is here:
Thanks,One line summary
Write a list of all the CSS classes used by the Joomla! 1.5 core.
For each class note where it is used and if possible illustrate its use
with one or more annotated screenshots.
The document should comply with current Joomla! Editorial Style Guidelines
and guidelines for the Template Tutorials Project.
Documentation written for this task must be made available under the
Joomla! Electronic Documentation License.
Prior knowledge of CSS would be useful.
Document as described above.
Extra Credit (optional)