Hooking up a subwoofer and speakers?

I poked around and searched but didn't find what I was looking for.

I have a whole speaker system 5 speakers and a subwoofer for my PC and I took it apart to hook up to my iMac but then found there is only one hook up on the back for audio and my subwoofer has 3 hook ups for front, rear and sub center.

Is it possible to hook up this type of system. The stereo that comes with the iMac is just not loud enough and what I want for sound.

Thanks in advance.

Lucy Goose

You can use an external sound card to do it. See this LINK for some ideas and prices.