To learn how to script in mIRC there are various tutorials out there on the WWW. Lots of help can be found in
/help, it's good to learn about Aliases and popups first before going on to fully fledged remote scripting, and then some more advanced stuff like using COM objects.
Some good tutorials can be found at
mircscripts.org and
mirc.net. You may also wish to search
Google and see the
More Info section of this site.
As an FYI, mIRC has it's own scripting language and is not the same as C#.
Regards,