Wallpaper, Brush and Levels

Make new layer, named brush. I want to make the picture darker, Like night day. I use brush tool, with hardness 0%. 

Brush the light area. Make it darker

After that, I want to make the balloons be lighter. Because in night, we can see the light from balloon. I use "levels" to make it lighter. Click layer-new adjustment-levels.

I make balloons be lighter one by one. So, change the layer's name be balloon 1, balloon 2 until balloon 8.

Finish make it be darker and balloons be lighter