1) I am used to with the Microsoft Window
2) I am not familiar with the Macintosh OS
3) I have a MacBook Pro, and I want to upgrade it to Mac OSX Lion
4) In the procedure, I read that I have to provide "My Apple ID"
5) My question: What is "My Apple ID"? (would you explain a little bit of it) (Is it a license key like in windows with 25 digits characters or numbers ?)