How to delete an old ITunes account and music to add new music?

My brother gave me his old Macbook but it still has his ITunes account on it and all his music. How do I delete all the music and his account and add my music and account so I can sync my IPhone and IPad.

Follow these steps in OS 10.9.1…
- System Preferences > Users & Groups.
- Click the padlock icon and type your password.
- Click the + sign and name your new account, setting it to Administrator".
- MEMORIZE YOUR NEW PASSWORD.
- Quit System Preferences, and if you get a message about auto-login, agree to turn it off.
- Restart, and log in to your new account.
- System Preferences > Users & Groups.
- Click the padlock icon and type your password.
- Select brother's account.
- Click the - sign to delete the old account, and choose to save as disk image in case your brother forgot to save his stuff.