FTP nightmares

It has been a long time since i had to set up access for an ftp user on our ftp server. Can anyone point me to a comprehensive step by step that will show me how to do it? I cannot seem to recall all the steps. I need to add access to one directory in the ftp only, and cant seem to get it right. I know i did it properly before, for myself, but cant seem to do it again.