chrash course needed!!

Hi guys. I need a crash course in a mail server setup. I've been reading a
lot of documents and I am getting very confused. I don't know where to
start. So I got some questions which you guys probably smile at, but please
don't tell me to go and get me another hobby J



I installed on a FC2 machine Postfix, Dovecot and Mysql.



Now my questions are:

1 How are virtual users created?

What is Mysql used for with Postfix?

What has to be done to tell Postfix to use Mysql to do whatever it does?

Why cant I telnet to port 25 from another machine? Only localhost works.

I do not have a domain to work behind. I'm just fiddleling with this on my
home network. Any suggestions for that or warnings even?



Why I am doing this? My intend is to set up such a mail server at my work
and that rather sooner than later. But at this point there is no hurry yet.



That is all for the moment guys,

thanks in advance for your patience and help,

Ragnar W.