Linux (Ubuntu) Install Total Security

Hi

Firstly let me admit I don't know much about Linux, but wanted to have play, so installed it on an old laptop. Then thought 'Secuirity' so tried to instal BD. Ah! not that easy if at all posible. I know some people say Linux doesn't need security, but better safe than sorry. So is it posible and if so how the hell do I do it, remeber Linux I know nothing!

Thanks in advance

Stuart