Can anyone help please i have purchased a macbook - my first mac
and i need to know what type of security i can put on there which is free as i am not sure if there is any on the macbook

There is never any good 'free' security to protect your computer. Macs are very good in themselves at protection against online threats. However, if you value your files/documents then I would suggest you get Norton Internet Security. It's not expensive and probably invaluable in protecting your hard-drive. Believe me, once you have been attacked by a virus or hacker - you will pay loads of money to make sure it doesn't happen again! A few pounds for peace of mind is invaluable.