Posterizing the Stairs

First of all I opened the original image in PhotoShop.

Mind the Gap Original

I then posterized the image by going to Image > Adjustments > Posterize and set it to 3.

Mind the Gap 1

I rotated the canvas by going to Image > Rotate Canvas > 90 CCW.

Double click on the Background Layer in the Layers Palette to unlock it. With your image layer still selected go to Filter > Artistic > Neon Glow and applied the following settings:

Mind the Gap 3

I then selected the Text Tool and chose the following settings:

Arial Narrow
4pt (very small)
Colour - FFFFFF

I wrote out the text mind the gap. I then went to Edit > Transform > Rotate and then used the Move Tool to position as shown below.

This is the final result:

Mind the Gap Final