Here is the result after masking. The masked part is supposed to be the entrance of the chamber.
Now we will add some cloud texture behind the entrance. Create a new layer again (Shift+Ctrl+N) below the solid color layer. Go to filter > render > cloud to create cloud texture.
Then give this cloud another filter, surface blur to smooth the texture. Go again to filter > blur > surface blur.
Duplicate (Ctrl+J) this cloud layer on time. Set this duplicate to exclusion blending at 100% opacity.
This cloud texture will be not entirely seen because its position is below the solid color layer. It is just visible in the masked part of the solid color.
Now we will add another object to the scene. Open the stock image in photoshop. Take the pen tool (P) to cut out the iron handle from the image.
Add the cut out to the main scene.
Now we will add light coming from the right side behind the right wall shining through the entrance. To do this, create another new layer (Shift+Ctrl+N) above the two cloud layers. Take the brush tool (B) use the settings in the image below.
With white color, stroke the brush repeatedly from the top right side of the entrance down to the bottom.
Referring to the light source, there should be some light cast on the left wall. So we will give some highlights to it. Go select again the left layer. Create a new layer with a clipping mask above it. Take a very soft round brush (0% hardness) set at a very low opacity of about 10-15%. On this layer, paint soft white to add some highlight on the left wall.
Proceed to give the whole scene color adjustment layer. Firstly, go to layer > new adjustment layers > brightness/contrast. Make sure to position this adjustment layer above the other layers. Set this layer to normal blending at 100% opacity
Give the second adjustment layer: color balance. Position this layer above the brightness/contrast layer set to normal at 100% opacity.
Select the two adjustment layers. Hit Ctrl+ G to group them in a folder. Name this folder adjustment. Go to layer > layer mask > reveal all to give this folder a layer mask. Mask areas around the entrance.
Now we will give some shadow and highlight to the walls. We start to this on the right wall. Select the layer again and create another new layer with a clipping mask above the brick texture. Take a very soft round brush ( 0% hardness) set to about 10% opacity. With the combination color of black and white, paint the shadow and highlight where needed.
Do the same way to add some shadow and highlight to the other walls.
Next, create a new layer again (Shift+Ctrl+N) above the adjustment folder. On this new layer we will add more shade and highlight to the overall scene. Take the brush tool again (B). Paint soft combination of black and white to areas where needed. Here is one for your reference – set in white background.
Referring to the given color, here is the result set to normal at 100% blending.
And this is the result set to normal at about 75% opacity.
In this step, we will still add some more shade on the area around foreground walls and floor. Create another new layer (Shift+Ctrl+N) above the previous shade layer. Take the gradient tool. Set foreground color to black. Choose a linear gradient set to above 10-15% opacity. Click-hold and drag the tool from the lower bottom upward as indicated by the orange arrow.