All scripts can be done in just the Remotes window. You *can* put aliases in the aliases tab and popups (menus) in the popups tab, but it isn't necessary.
To create a new window, use /server -m irc.server.net ... the -m makes a new window.
To access things in the help file, you'd use stuff like:
/help on connect
/help /server
/help on start
on START will start things when you start mIRC. on CONNECT will do stuff when you connect to a network. Examples are in the help file.
An example is:
on *:START: {
server irc.network1.net 6667 -i nick -j #chan,#chan
server -m irc.network2.net 6667 -i nick -j #chan,#chan
}
on *:CONNECT: {
if ($network == network1) {
login password stuff
}
elseif ($network == network2) {
Do something if needed
}
}