hello bros out there....

i need some real big help here.. going nuts trying to figure out how to solve my own mistake..

i have a laptop , ACER 4745G... which has S/PDIF digital output.. some DOLBY 5.1 thing..
and it only has 1 output jack.... the headphone jack..

and then i bought a Edifier 5.1 which has 3 line ins... for
1) centre + subs
2) front LEft Right
3) Surrond LEft Right.

so i have a problem now to connect this to my laptop...
i read online u need to get a converter or someting ???
please HELp....