Ha, I guess the account was set up by a guy in the shop right?
So, you have to log in on a computer, not on the iPad-Pod-whatevs. Then go to the settings, click on "Accounts" at the top, and there is a part that says "Send mail as". You can change it there: click Edit info, and put your name.
And while you are at it, you must also do this for the safety of your account: go to settings-accounts again. This time click on "Change password recovery options". You will enter your password again to verify it's you, and then you must put a recovery email address and it is preferred to also give a phone number. It is important to do this because if you forget your password, you will use these to get back in the account. If you don't provide this, and forget the password, you are screwed.