Then go Select- Load - Selection and choose Alpha 1 to select the chain, go Select-Feather and set the Feather Radius to 1 pixel then Edit - Copy (Ctrl+C) to copy the chain selection. Save and close the chain.psd file and go back to the Shipyard.psd file. Edit-Paste (Ctrl+V) and name the new layer chain. With the chain layer selected go to Edit-Transform-Scale (Ctrl+T) and by pressing Shift scale the chain a bit, now use the Rectangle Tool (M) to make a selection on the last upper two chain link Edit-Copy (Ctrl+C) and Paste (Ctrl+V) name the new layer link, then go Edit-Transform-Flip Horizontal and drag it under the ship layer. Select the chain layer again and add a Layer Mask and use a Round brush to mask out the part of the chain that is covered by the ship and the roof, using the Layer Mask is great because you can try a lot until you have the desire result, you just have to change between black and white to add or to subtract part from the chain. When you are happy with it click on the Create New Layer icon ,drag the layer under the chain layer,select the chain layer again and go Layer + Merge Down (Ctrl+E) name it again chain, now do the same with the roof layer but name it roof. Also Merge Down (Ctrl+E) the wall layer with the ship layer. Change to the link layer and arrange the two chain link behind the ship to look believable.
Now we have to set some shadows. To do that Create a New Layer (Shift+Alt+N) name it shadow and place it under the chain layer. Now activate the chain layer and Ctrl+click to Load Selection, change to shadow layer now and go Edit-Fill (Shift+F5) to fill the selection with black. Use the Arrow keys to move the shadow down and left a bit and then go Filter-Blur-Gausian Blur and use a 2.5 pixel Radius and then use the Erase Tool (E) to get rid of the shadow under the sail. With the Polygonal Lasso Tool (L) make a rectangular selection around the shadow that lies in the dark area of the roof with the selection still active go Edit - Transform - Distort to move the shadow under the chain.
Now using the same techniques move the bottom part of shadow, on the roof under the chain and set the Layer Blending Mode to Soft Light.
For the next step open the canon .psd file on the images folder and use the Pen Tool (P) to cut out the canon and to make an Alpha Channel from the selection like we did for the roof and the ship. Once you done that go Edit-Copy (Ctrl+C) and save and close the canon.psd file. Go back to the shipyard file and Edit-Paste(Ctrl+V), place the new layer under the ship layer and name it canon.Go Edit - Transform - Scale and Rotate to position the canon like in the image.
Now use the Dodge Tool(D) with a big Round soft brush, Midtones - Exposure 20% to lighten a bit the chain where the light falls on and the Burn Tool(O) Midtones - Exposure 20% to darken the chain on the bottom and on the dark side of the roof, and the ship part where it collides with the roof. Select the chain layer and then link all the layers, go Edit - Transform - Perspective and by pressing Shift slightly drag the upper felt corner to the right and the the middle point to the right, like in the image.