Password and username established by Apple Staff during personal setup

I recently purchased a mac and had the fabulous Apple staff transfer all my data from my PC. In trying to install my Blackberry software to my new Mac, it's asking me for my password. My admin user name is simply my first name, but no one ever told me that I had a password. I've done some research and I'm being told I need to reinstall my operating software... except I don't have any! Is there a default password that may have been used, or should I make an appointment with Genius bar? I don't mind doing this, I just don't want to waste time.
Thanks!
Jill