Installing Aftermarket Head Unit in 2003 Ford Taurus SES?

I can t figure out the wiring situation. I got the harness that runs all the way back to the trunk; however, it only has 9 wires. Two for each of the four speakers (8) and one to control an amp if applicable. However, while the wires from the head unit have two power wires, the harness has none. The head unit I got is a DEH-X6700BS. Please help, how do I power this head unit when the wiring harness has no wires for power, only speaker wires?!

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