Can't see enough detail, but you can't just move a disc brake any old how. You need a wheel with a hub that has a rotor mount and you need a frame that has mounting points for the disc brake caliper.
And for a bike that's currently available at $130, anything you have to buy to make that switch a mechanical possibility will also turn it into financial stupidity.
About the only fix that would make sense is to get that disc brake into decent working condition again.
Try to explain what's wrong with it wit more detail first.
You do know that brake pads need a bit bedding in before they work ok, right?