Require custom inputs upon registration

I'm new to all this, I would like to require that new users have to enter additional information (Company name, address, an explanation in a text field, etc.) upon creating a new account. I don't want all of this to necessarily be public, but be used by staff to determine if the user can have access to the forum or not (I have "requires approval" activated). Can't seem to find where I can do this?

Help would be appreciated, thanks!