Inside the IF parentheses you state a value, an operator and another value.
If ($nick isop #) will translate from mIRC code
$nick == Nillen - #Nillen
So it will literally look like this:
If (Nillen isop #Nillen)
You can put whatever value you want there instead of $nick, your X.
var %user $2
var %channel #Nillen
if (%user isop %channel)
Useful reads:
/help aliases
/help variables
/help $nick (the first one)
/help if then else