First of all, find out what the network address of the network the channel that you want to join is on (format irc.-----.---) and also the channel name (format #------).
Next, start mIRC, and it should pop up a menu. Fill out your nickname, name, and email address (they don't really have to be real) but you don't have to worry about the server options. Press OK.
Next, in the blank window there should be a bar, which you type the command "/server [server address]" to connect to it. After it finishes connecting type "/join [channel name]" to join the channel you want.
Also, I think MBread has its own irc channel but there's also one on irc.deltaanime.net, #MeltyBlood, that you can join if you want to. We always welcome new people. =D