Having the turret portion of a tank aim to where the position where mouse's hit

So I’m trying to figure out using motor6d, how to move around the direction the cannon of the tank points to.

I’m just going to be straight forward and just give the model I plan to use the information I wil gain here.

So the important part of the model is “head” and “body”, for now I just want the model to only rotate the “head” in its the y-axis, as it points towards the position of the mouse. . I’m trying to understand how I can preform that by modifying C0 and C1, but the mathematics of the cframes eludes me.

I don’t want a script, but a broader explanation of how c0 and c1 interacts each other would be very helpful as this isn’t the only thing I need to apply this knowledge on…