IF you have a basic understanding of how a sniffer works, you wont need a single document when using ettercap to sniff cleartext connections.

What you have failed to do is provide detailed information on what you want to do. For example, what kind of password? FTP? Telnet? Also, placement of the sniffing host is very important. If you place it on a switched segment, you may find yourself faced with an additional obsticle before you can begin to analyze traffic. Are you on a switched network?

Now then, how about giving us additional information and perhaps we can be more specific.