[No-1]
Open a blank document of 1280 x 1024px and fill it up with black color

[No-2]
Now Go to> Filter> Render> Clouds and apply clouds, before applying clouds filter, make sure you have selected default colors black and white

[No-3]
Now Go to Filter> Pixelate> Mosaic and adjust cell size according to your need

Now we will have something like that after applying above filter

[No-4]
Now to make our cell’s edges look more clear we will apply Reticulation, for this goto> Filter> Sketch> Reticulation and apply the following settings

now as you can see we have sharp cell edges with sharp colors

[No-5]
Now its time to add some glow to our cells, for this goto>Filter> Sketch> Photocopy and apply the given settings

Now you’ll have something like this

[No-6]
Now we have to invert its Colors by pressing Ctrl+I

[No-7]
its time to add some colors into our cells, for this Go to Image> Adjustments> Hue/Saturation or shortcut Ctrl+U and apply following settings or you can use your own colors.

now this is what we got after applying colors

[No-8]
Now we will add some perspective to our wallpaper, for this Press Ctrl+T and Select Perspective as shown

[No-9]
Now Make it look similar as i did below


[No-10]
Now create a new layer in the background and fill it with black to cover the transparency

[No-9]
Now open blending option of our Mosaic layer and apply outer glow to this layer with AD005E Color

We are Done…!

