I have these old speakers and i dont know how to put them to more use.?

I have 2 speakers and each have a wire that comes out the back and is stripped and splits into two pieces then its spposed to go into the black and red things in the back of the stereo and ultimatly plays music. But what if i have only the speakers? what can i connect them to? Is there a way i can change the end to have a 3.5 mm jack or something? please help me...