Hello DClause and welcome to the forum. This shouldn't be too hard to figure out, but we probably need a bit more information about how your system works or used to work.
Before you added the second tank how did you fill the fresh water tank? Was it a gravity fill on the side of the trailer, or by hooking up the the city water connection and flipping a lever?
When you say the system is pumping water into the tank, can you be more specific on the failure?
Is the pump moving the water from the new tank to the original tank?
Does the pump run and fill a tank if all the faucets are turned off?
Do you still have a city water hose connected to the side of the RV?
Do you have a winterizing antifreeze hose and valve by the pump and is it set correctly?
Did you disconnect or move any hoses by the water pump, or only down by the tanks?
In your picture there is a T fitting wrapped by a piece of wire. Where does the connection that goes up out of the picture go?
Where does the hose with the two screw clamps go? Is that a vent line?
