MacBook Pro 15 & Audio 5.1 (3 Jacks)

Hi guys,

i bought a macbook pro 15. I know it has an optical in/out for audio. At home i have a 5.1 speakers - precisely a philips MMS 260/00.

I really don't have any idea about how i can connect my speakers on the macbook pro cause it has just 1 1 optical input/output and my speakers instead have 3 jacks (green, orange and black).

Could anyone please tell me what i need and how i can connect this speakers (with 3 jacks) on my mackbook pro?

Thanks in advance

DS