Wow, Deanna, you do need some help. I've never used heat cord so I don't know. Have used heat tape with good results. I lay it along the pipe and then cover the pipe and tape with the foam pipe insulation. I'm not sure I'd put anything on pipe in walls though.
Is this an exterior wall? Can you access the pipes? Maybe just slide some foam pipe insulation up the pipe. Can you open up the wall to get to the pipes and just let the heat of the house keep it warm? Can you get some insulation into the wall cavity?
I know of an exterior faucet and main water inlet valve in an exterior concrete block wall that kept freezing up. It had a solid wood access cover to it. I took it off and installed a return vent cover over it to allow heat into the wall cavity.