First you'll need to get a copy of the wzdftpd source to make and test your changes. Use Subversion to get the source so that you can easily generate your patch.
Bug fixes for a current release may be added on the stable branch:
svn checkout http://svn.wzdftpd.net/svn/wzdftpd/branches/rel-0-8-patches/ wzdftpd-0.8-stable
Features should be added on the "trunk" development version:
svn checkout http://svn.wzdftpd.net/svn/wzdftpd/trunk wzdftpd-trunk
