I bought a cheap new loaded pickguard (HSS) to install in my Squier Affinity Strat. It looks great and it has great reviews, however I am confused by the wires. There are three wires: one red and two black. Picture

One black wire is connected to the volume pot itself. Another one is connected to the metal part of the pot and also the little thingy on the side (sorry, I don't know what it's called!) the red one is only connected to the side thingy.

Which one is ground (connect to tremolo area thingy), and which ones are for the input jack?

Thanks, this has been frustrating me for the last few nights!
The black wires are both ground. One goes to the sleeve of the output jack, the other gets soldered to the back of the trem claw to provide grounding to the strings. It doesn't matter which one goes where.

The red wire goes to the tip of the output jack.