To be precise, you'll need to find a repair manual specific to your engine's displacement. A Haynes or Chilton manual for your year and model would be a great resource, showing diagrams and locations clearly.
Generally, you'll find them in these areas on the engine block:
* Behind the timing cover (front of the engine): Often several are located here.
* On the sides of the engine block: Usually at least one or two on each side.
* At the rear of the engine block: Potentially one or more here as well.
Without knowing the exact engine in your 2006 Charger, I cannot give you precise locations. Searching online for "2006 Dodge Charger [your engine size] freeze plug location" might yield images or diagrams. However, relying on a repair manual is the safest and most accurate approach.