hi, guyz

i hav a mp3 player...umm... i wana play it using my pc speaker since my room doesnt hav any audio player... but my 5.1 setting logitech speaper has 3 cables which one to front center, one to front two speaker, one to rear speakers... so since i hav only one cable for mp3 player how can i connect mp3 to 5.1 setting speaker? do i hav to buy any extension cable or wuteva? what can i do? pls hlp me....