You can go about this many ways. Seeing as I use photoshop and can move layers I started with the bike.
step 2 of 4
Next I created a basic street and sidewalk. Followed up by the startings of a building. Created a text line. Sized and then added inner and outer glow. The door was made by using a texture filter on the door. Duplicating the layer and then removing parts of one of the layer to show the other layer's lesser opacity.
step 3 of 4
Next I crated a cigarette can, trash cans, and moved the buildings around more to my liking to work on perspective.
step 4 of 4
Adding people is purely based on your own imagination. My initial idea was going more Bladerunner looking but ended up not. I also wanted a few of them to act with each other so the guy is looking back at the girl who is flipping him off.