Plasma TV Audio out.

Question

I just purchased a room cinema system ( Samsung RTS-HE10T-HTK) but can not get my Plasma TV (LG 50PG40) audio connected to it, the only Audio out i can see on my TV is the Optical digital out and the only audio input on my Cinema system is the AUX. the manual mentions that this port is for MP3 players etc. can i connect the TV optical out to this AUX, if so, what do i need to buy.