Disadvantage of raster based programs:
Enlarging images causes it to become "funky" and lose data.
Dodging - lightening the image (set to 10% and according to what you're changing [ex: midtone or shadow])
Burn - darken the image
Adjusting the Brightness of the Entire Picture In Photoshop:
Image > Adjustments > Curves
Light parts of a photo.
Regularly lit parts of a photo.
Dark parts of a photo.