There are a number of Drupal SEO modules to choose from.
Start by using the newest 6.x version (7.x isn't yet ready for production) and manually put the »sites/default/settings.php« file. Walk through the standard installation process to configure database and admin login.
This set of modules is needed by almost every project, so just get them and don't ask :)
All core modules and files can be found under http://api.drupal.org/ where most of the additional modules are referenced here http://drupalcontrib.org/.
Markdown is a text-to-HTML conversion tool for web writers written by John Gruber. Markdown allows you to write using an easy-to-read, easy-to-write plain text format, then convert it to structurally valid XHTML (or HTML).
Thus, Markdown is two things: (1) a plain text formatting syntax; and (2) a software tool, written in Perl, that converts the plain text formatting to HTML. See the Syntax page for details pertaining to Markdown’s formatting syntax.