Fix a single dark brightness area in the photo!

Is this the pic you want to correct or have you disguised it for posting purposes?

There are a number of methods, the way I darken or lighten parts of an image is:

Insert a blank Layer above the image and Fill it with 50% gray (Edit > Fill.. select 50% Grey from the Contents dropdown menu). I then set the blending mode to Overlay (you can then see the image under the grey). Set the Strength to around 10%. You can then use the Dodge tool to brush to lighten areas of the image (choosing a soft edge and size to suit) and the Burn tool to darken areas (all non destructively) you can then use the Opacity slider in the Layers palette to fine tune the effects. If you prefer, you can use two Layers – one for darkening and one for lightening.