Mac Forums

Today is Friday the thirteenth and my luck has been kind of sucky.
I got a mac book pro today and started doing what any new user would do. clicking on apps, exploring settings etc. I messed with some privacy settings and in the process did something wrong without realizing it. And then I logged out... then the screen turned gray and i was asked to provide a name and a password. So the thing is I know my password but I don't know my user name.
Please help me!!!! I am a new Mac user with some unfortunate luck
thank a bunch!!!