Now we need it to look like its an entry, so with the rectangular marquee tool, highlight the duplicate layer and make a selcetion of the wall hold down Crtl and press C to copy a section of the wall. Paste to a new layer by holding down the crtl button and pressing V. Make sure to move the layer above the black doorway layer.
Move the selction in the doorway and use the transform tool to shape it to look like the inside wall.
Create a mask on the layer and use the gradiant tool to create a fade. Start from outside the doorway to inside from x to x on my image.
Last thing is to fix the the door step and we just repeat the steps we did for the inside wall.
And there you have it.