OT: FTP Server for the technical guru's

[brian_wagner at sbcglobal.net (Brian Wagner)]

All right I have decede to setup an FTP server at the house and I run DSL with PPPoe through SBC.
 
Internally I can connect to the server no problem, it is the external IP address that is giving me the problem. When I set it up and try to connect using the external IP address (which is static, and I test this through an FTP client) the trace log for the client shows connecting and then times out because it can not create a socket. In the Server stats it show I am trying to connect and then Error with no description.
 
My question is how can I do this? Or can I do this with the PPPoe? 
 
If not what is a DMZ? And do I have to subscribe to one? or do I set it up on my router? 
 
As you can tell I am stooooopid when it comes to this, so speak in dummy terms.
 
TIA