Distort the shadow on the necessary direction (opposite one from the moon), using: Edit ? Transform ? Distort.



Blur it out (Gaussian Blur).



Change the layer's Blending Mode on Soft Light.



Then select the Brush Tool of star shape and the Eraser Tool and place the stars in the box:



Make a copy of this layer and blur out the copy (the same way we did with the stars on the sky) and change the color of the blurred layer (It's necessary for it to be placed under the basic layer), using Image ? Adjustments ? Selective Color.