First take a photograph of the skyline of the city whose website you wish to make. In this case I have take Seattle. Try to choose a city that has one prominent building. Like Singapore has the Petronas Tower and Agra has Tag Mahal.
Next using the pen tool make an out line of the skyline of the city and fill it with black color. You can also choose any other color of your wish. After that also add a background color.
Now again using the pen tool make the shapes that are shown below and add it between the city skyline layer and the background layer.
Once you have done that you will get something like this.
Just add the other parts of the website and your website is ready! Here have a look -