hello, looking for some help with a Dodge Ram with the factory amp has been removed

Hello, JR here, i am not a audio geek but i have installed a few head units. Im looking for some help with a truck i just purchased. its a 2006 Ram with the infinity sound system. It has an aftermarket radio but it isnt hooked up atm, the last owner had removed the factory amp, and has his own am and sub installed. When he sold it he pulled most of the stuff with it and said, it "just needs a new harness" So I have messed with this and cant get a single sound out of the speakers.

If I need to make this post somewhere else , im happy to do so if you will point me in the right direction. Or if you know of a youtube video that will help, im all about it.

Thanks for letting me join and hoping to find some help.