Step 1: You have two separate pictures of a light bulb and a screw, first line the screw up with the light bulb, and create a layer mask of the screw layer and use the brush tool to rub out the unwanted lines from the picture of the screw inside the bulb. Then add a new layer, name it clean up and use the eraser to get rid of the black in the background. Create another layer and use the patch tool get rid of the metal rods in the light bulb and other marks.
Step 2: Now you have an image of a stick and you need to add a mask layer to the stick layer and erase the background of the stick image. Also you have a picture of a tree top, add a mask layer to this and using the brush tool rub out the trunk and branches to leave the leaves, reposition the tree top so it looks like the stick is holding it up.
Step 3: Duplicate the tree top layer you've just done and resize and warp the image to make it fit the thin part of the light bulb to create a shadow shape and then add a layer mask to it and use the brush tool to erase the tree that's outside the light bulb still and to merge the tree into the background to create a shadow. Repeat this again on another duplicated layer of the tree but do it at the top of the light bulb. you can change the colour of the tree by selecting its layer and changing its hue and saturation( command u).
