First we’re going to light the stars. Create a new document and fill it with black. I’ve set the dimensions to 1600×1200 so it can be used as a wallpaper in future. Duplicate this layer.
Go to Filter – Noise – Add Noise. Set Amount to 10%, distribution to Gaussian and check Monochromatic.
Go to Image > Adjustments > Brightness & Contrast and set Brightness -30 and Contrast 75. Now the noise begins to remind stars.