Clean URL for custom content
Enable Clean URL + get Pathauto module, which allows to define custom URL patterns for every type of content

If the Clean URL test fails, the web-server is not configured to support this feature. You need to configure the web-server to support Clean URL.

With Apache HTTPD as web-server, you have to enable mod_rewrite and configure the necessary rewrite rules. The rewrite rules can be found in the .htaccess file that comes with Drupal. Usually, theses rules are applied automatically, when mod_rewrite is enabled, but in some cases, the AllowOverride directive is too restrictive to allow this.

See Clean URLs in the Drupal Installation Guide for a more thorough introduction on how to get Clean URLs working in Drupal.