Well, judging by the fact your using !addop, i'm going to guess your trying to make an auto-op script.. in which case you should probably look at: /help /aop - this is mIRC's built in one.
If you still want to write the 2nd parameter to a file then:
$1 - is !addop
$2 - is the nickname so..
/write "C:\store me\here\myfile.txt" $2
^ for example.
Eamonn.
