how do chmod a directory in drupal I want to enable pictures for users in drupal http://drupal.org/node/22271
and I am not sure how to chmod the directory so that users can save their pictures in it.

Thank you for your help in advance.
You want to go through this guide.  It discusses in depth the appropriate filesystem permission settings you should have on every part of the Drupal installation (public files, private files, etc.)  If you follow that guide to the letter your filesystem problems will sort itself out, and you'll have a more secure Drupal installation.  Let me know if you have any questions.