How to connect a subwoofer to a new stereo

[rafecior]

Hi, I have a Chinese Android radio, 4 speakers play ok.I recently checked that there is probably a subwoofer in the Ford.How to check if it is really there, which cables to connect to hear if it works without removing the upholstery. All I need is information about which cables activate the subwoofer - from which connector, whether power needs to be connected, or whether only audio +/- is enough. In the stereo photos I had earlier. I also have a sub output in the new stereo. I'm also posting a photo of the view under the casing at the back of the car. Expedition 2008 limited 4WD. Thx.