Authentication

Hmmm... Someone asked me about this today and I don't know how to respond. If you create a custom user profile field (homeroom, for example) and you want to upload users via a text file, how do you edit the text file to accomplish this? Do you simply add Homeroom to the list of fields like this:
She says she has tried this and it did not work and when I try it I get the following message: "homeroom" is not a valid field name.

Any advice for me on this one?

Thanks,
Art