Since i'm not entirely sure we are all talking about the same thing, to help you understand the different things and clarify:
You said "the program" wants a passwd. Do you mean when you open mIRC, before you connect to any server, a box pops up asking you for a passwd? Or do you mean that once you are connected to a server that you see a msg asking you to identify for your nickname? (you opened mIRC, clicked on connect, see a bunch of stuff scroll by in the status window about the server and then see something like if this is your nick you have to identify to it blahblah)
If, as i think, you mean that the problem is with a nickname you registered (not registering your copy of mIRC, thats totally diff, as is setting a passwd to lock mIRC from use) then you need to do as suggested, ask in a help channel on that network or look at their website for how to register a nick, how to complete that registration if required, and how to identify to your nick.
You do not put the passwd for your nick in mIRC's options under file/options/connect/identd, the user ID line. That usually needs to be whatever you have before the @ in file/options/connect, the email addy line. The line /nickserv identify putting-your-password-here (like /nickserv identify chicken (if that was your password)) would be typed in the status window after you connect to a server. (and no, you dont use any <>)
When you registered your nick, YOU would have set a passwd for that nick. Like maybe /nickserv register chicken [email]somebody@some.net.[/email] chicken would be the password and
somebody@some.net would be your email addy.
mIRC is software (a program) used to connect to networks (like DALnet, Efnet, Gamesnet etc) using the servers for each network. Registering nicks is different on all networks, they each have their own procedures, so it wouldnt be possible to cover that on mIRC's homepage or FAQ, but you made my day by saying you looked!