lighten up the dark photo

1-open the photo then duplicate the background layer.

2-go to Filter>Blur>Gaussian Blur.. then change the settings just like this pic :
you can change the radius amount depending on your photo size (the bigger the photo the bigger the amount)


3-now duplicate the Layer1 then go to Filter>Distort>Diffuse Glow.. then follow the pic:
and also you can change the amounts depending on your photo size



4-change the blend mode of the two top layers to screen just like the next 2 pictures :



this is the result so far :


it's good but the sunlight area is too bright so in the next step we will work on darken it a little bit

5-now we will group the 2 top layers select both of them (select the first and while you are clicking on Ctrl select the second ) like this :


now group the 2 selected layers by pressing Ctrl+G or go to Layer>Group Layers:


6-add a layer mask to the group :


select the gray color:


now finally paint with medium brush on the too bright area like here :
(paint on the red area in the next pic )


this is the final result :



and this is another example :