I see your trying out the gradient. Thats exactly what I'm learning to do.
You know lemme give you a tip, constructive critisism....although it aint really criticising:
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1st. Take a picture with a nice balance between dark and light.
Then decrease saturation with half in the Image>Adjustments>Hue/Saturation section.
Then make sure the light areas are light and the dark areas are dark by using a BIT of "levels" adjustment. I notice that you should drag the white triangle more to the left than you should drag black to the right. Maybe you should already add +10 contrast. Make sure you dont overdo it...yet though, see final result on how to judge this
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2nd. Create a new Layer from Copy. This is just the same layer wich you can adjust with opacity.
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3rd. Now take a bit of gradient.
-Change the opacity of the gradient to about 10% first.
-Then if you look on top you need to have the star shaped...shape. It's called Diamond Gradient if you hover over it for a sec.
-And click the bar with the grey white squares and change it into [your selected gradient color] > going into transparent.
-Now drag a layer of gradient from the top right corner to the bottom left corner and vica versa.
-Now go to the layer screen on the right and change the opacity of the layer so that the gradient doesn't stand out and make it ugly.
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4th. Now go ahead and increase only the contrast with +35 and if you havent previously gone overboard with levels in step 1 you should end up with the gradient only visible in the medium colored areas. The highlights remained white and the shadows remained dark.
You can still adjust the Layer Opacity.
If the light and dark areas are still affected by the gradient too much you should go to "levels" again and drag the white and the black triangle a bit towards eachother. Or much maybe...depends.
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This took long to type but really I just made 5 versions of one picture in my gallery in 10 minutes just now

Feel free to take a look

And this is the result I got with your picture. I used all the numbers I described here so I explained it pretty accurate and adjusted it along the editing of this pic.
It's subtle but contrast and gradient opacity can change that if you want
