For quarter inch plugs and jacks, the center tip of the plug and center contact of the jack are always positive and the body/shaft of the plug and outer ring of the jack are always negative. When color is involved, red is positive and black is negative. There are volumes and volumes of these basics on the Internet. The more you learn of these basics, the less you need to go to professionals when minor things go wrong.
Note: The above can be reversed, but usually only on DC power supplies, and they almost always list which is positive and negative on the item. But we was talking speakers here.
I just typed out a long post explaining wiring speakers as water running through a series of pipes, as that is how I learned basic electricity. However, let's simplify this with pictures. Go to the link below and click on the link at the bottom, left of your screen entitled Speaker Wiring. Why they could not have used two speakers diagram in the basic parallel picture, I don't know. Just cut half the picture out for what you want to do.
http://www.usspeaker.com/homepage.htm Note: Getting a speaker out of phase literally has one speaker fighting the other(s). When one goes out on the cycle, the other is moving inward, instead of both pushing and pulling air in unison. This is a hack explanation, but the basic idea is there.
BTW ? Welcome Angel!
