Adding my email address -MacBook When i purchased a new Mac book and turned it on for the first time, there was a pop up where i had to enter my name, address, email etc.

I skipped the email field, and now in xCode, my name and my company name gets displayed as comments and not my email address. So how can i get my email to get displayed in xCode in the comment section ? 

note: I only want my email ID to be displayed in xCode and not in other applications.
By default, Xcode does not include your email in the automatically generated headers, regardless of whether you gave it to your Mac or not.

However, if you want to change how the automatically generated headers look, navigate to Xcode.app, right-click it, click on Show Package Contents, then go to Contents/Developer/Library/Xcode/Templates/File Templates. There you will find the templates Xcode uses; feel free to edit them to include your email address.

Note: the above assumes you have the latest version of Xcode, which is installed as an app, with the Developer directory inside the app bundle. If you have an older version, you'll probably find the templates in /Developer/Library/Xcode/Templates/File Templates instead.