Type /help scripts and start reading
Try some of the examples in the help file, understand why and how they work, play around with them, test some changes and expansions, go to a scripting site like
www.mirc.net or
www.mircscipts.org, look for basic tutorials and read and try those, also check out snippets on those sites and try to understand how they work. This can come down to using /help to lookup each and every /command or $identifier...
Once you feel comfortable with basic scripting, you can start writing your own, and reading more advanced tutorials. Don't be afraid to test stuff out, use a separate mIRC if you need to and press ctrl-break if your mIRC ever hangs when one of your scripts has an error.
ps: yes, I know that you won't be able to do all above tonight, it takes time...
