Digital BW, The Print

I know how to do quite a few things is PS, but this I don't know. 
How do you burn in an area of a faded image to match the areas 
that are not faded? Or, how do you simply burn in an area of an 
image a certain color? Usually one color is faded and that 
causes the problems. If I knew how to burn in an area in one colr 
I could correct those areas of serious fading. If there is another 
way to do this let me know. I have a lot of negatives that need 
repair to one degree or another.
I have tried going to Adjust>Hue/Saturation>Master and played 
with the various chanels. However, that changes the whole 
image and I don't aways need that.

Thanks
Russ Martin