Change the lens flayer layer blending mode to Screen. Add a layer mask and paint with a black brush in the indicated areas.
Open the “Lens Flare” file. Make a selection of the top left sun with the rectangular marquee tool. Copy and paste into our image. Convert it into a Smart Object. Resize and position as shown below. Name the layer “Sun”.
Change the blending mode of the “Sun” layer to Screen.
Duplicate the “Sun” layer and move it in the tower of the bigger castle.
Create a new layer and change the blending mode to Overlay. With a white brush paint some highlights as indicated below.
Download the PSD