Sub woofer/Speaker set up?

Okay, so I guess asking someone to email me for help is considered spam. So anyway, I have a home theater sub that plugs into the wall and I'm trying to connect the sub to my computer speakers. The speakers are connected to my computer with an auxiliary cord. They work just fine, but when I connect the sub to the speakers using an RCA to jack cord in the auxiliary input in the speakers, no sound comes out, but when i plug the sub/ jack into the microphone port in the speakers, the sub will work, but the speakers stop so I only get bass. If you have any ideas or suggestions, I would appreciate them. Keep in mind that I have no previous knowledge on the subject. Thank you so much!