Um... 2 minutes is *hardly* time enough for people to reply. This is a forum and not AIM.
To connect to a server, choose your server in mIRC options (Alt-O), or if you know the server, you can just type:
/server irc.servername.net
Example:
/server irc.undernet.org
/server irc.irchighway.net
/server irc.phazenet.com
You could also provide more detailed information... it helps to know what you're trying to do. We have no idea what server you want, for example.