I am using emacs 24 on fedora 17. I installed markdown-mode, but whenever I try to export a file by typing C-c C-c m or C-c C-c p in emacs
markdown-mode
C-c C-c m
C-c C-c p
Install any markdown generating tool as you like, for example pandoc.
Then add the following line to your .emacs file:
.emacs
(custom-set-variables '(markdown-command "/usr/local/bin/pandoc"))