How do I retrieve the user name and email during signup

I am trying to programmatically enter the new users login name and email from their registration information. I cannot find a function to retrieve those two pieces of information from the database.

I would like to retrieve them from the current user information as soon as the newuser_notify_siteadmin() function has run.

Any suggestions on how, and possibly a hint of code for a non-coder?

Thanks,
Kirk