Help with 97 Mercury Mountaineer

I installed a aftermarket radio in my Mountaineer but even though it powers on, there's no sound coming through the speakers. The previous owner didn't put a radio in it, so no help there, and there was just an empty hole where the radio used to be, with a long skinny connector (for the power) and a small black square connector (for speakers) and wires, where someone had removed a radio previously. The right side, in the back has the factory amp but not the subwoofer, and there are JBL speakers in the front doors. Any ideas or suggestions on what I can do, other than re-running all the speaker wires by hand and splicing them in, or paying a chunk at a radio store? Do I need to run a hot wire to the amp? How can I bypass the amp if it doesn't work? Or will I have to replace it?

Run the 12V switch (Usually blue) from the headunit to the Blue/Black wire of the wiring harness. It'll work then.

Thank you!

Ahah, I assume it worked.

No problem.