These links from mircscripts.org might help you:
[*]
Starting out with scripting by blue-elf
[*]
Using dialogs by INSIDES
[*]
Dialog design by blue-elf
[*]
mIRC scripting tutorial by MadMonkey
In addition, have a look at the mIRC
FAQ (not the normal help file) available
here on this site, which provides step-by-step details on starting to "program" mIRC - remember, Section 7 is your friend!

Hope this helps
PM