We start with opening a new document in photoshop of 1280 x 1024 px dimensions, 72 pixel / inch resolution, and black as our background color.
Use the settings as it shown in the image above.
Now we have a new document with one layer filled with black color as background. Click on layer 0 and rename it to "stars". In this layer we are going to create stars in the background.
While selecting "Stars" layer, go to Filter Menu > Noise > Add Noise filter. Add Noise dialog box will appear on screen. In this dialog box select the settings as shown in image below :
Now go to Image menu > Levels or press CTRL + L . In Level dialog box change the values as shown in image below :
After doing this make a duplicate layer of "Stars" layer by doing a right click on the layer and selecting duplicate layer option. Rename this layer to "Big Stars". Now change the layer mode of "Big stars" layer to "Hard Light". Now press CTRL + T to transform this layer.
While transforming hold Shift key to transform proportional and drag one of the corner of "Big stars" layer outside the document window to make it larger then the "Stars" layer. We are doing this to make some of the stars look bigger then other for unssymmetry in background.
Till now we have only completed with our background. Now we are going to create Retro lines for our wallpaper. For this, first we have to create a brush preset.
Add a new layer above "Big stars", choose #545454 as your foreground color. Select Rectangular Marquee tool and make a selection of document height i.e. 1280px & around 50 px width. Fill this selection with foreground color and go to Edit Menu > Define Brush Preset to save this as your brush. Name it as Retro Brush.
Now select Brush as your tool and move to Brushes panel to make some settings for your new brush preset. In Brushes Panel select Retro Brush as your active brush and follow the instructions according to images given below :
Also check Smoothing option in brushes panel.It will be best practice if you play with all these settings, make changes in settings and test it yourself.
Now on a blank layer make a selection of height 1280 px and width around half of your document as shown in image below:
Rename it to Retro layer and paint some rectangles in the selection area. After doing this resize the layer by pressing CTRL + T or going to Edit Menu > Free Transform option. Increase its height and then rotate it 45 degree clock wise.
Now go to Filters > Blur > Motion Blur option. In the dailog box set the angle to 45 degree and distance to 350 px and click ok. Now we have image something like this :
Now we are going to erase some part of these retro lines, so select your Eraser tool with 35% opacity and 40% flow. Erase some of the outer area and corners of retro lines.
Now add a new layer above "Retro Layer". Change the layer mode to "Overlay". Now Press "G" or select Gradient Tool from toolbox. In Options bar, click on gradients to select a rainbow type gradient.
After selecting gradient, Use Gradient tool diagonally in same directions of retro line like this :
Add a new layer for "Apple logo". Please search for apple logo on internet. After that copy "Apple's logo" on a new layer in center. Change the layer mode to "Overlay". After this make one duplicate copy of this layer above this and make its opacity to 30%. Thats all !
and here we have completed the tutorial on "How to create a retro style apple wallpaper in photoshop".
Here is our final image. You can view the final image preview below or view a larger version here