Creating this merged colour background in Photoshop or Illustrator


I'm fairly new to designing and was just wondering whether if anybody knows how to go about creating the background in the image below?

Any feedback will be much appreciated.

enter image description here

8/15/2016 10:59:00 PM

That background is hand painted, using the Paint Brush tool.

A simpler method would be to use a three-color gradient, as I have below:

enter image description here

For a more personal touch, paint the sky in by hand. I have given a very quick example below, naming each layer with the hex value of the color I used. I used a large, 0% hardness brush. Add the stars in by using a small, hard brush and varying the size, either with [ or ] or by altering your brush presets to scatter and vary size automatically (my preferred method).

enter image description here

8/15/2016 6:40:00 PM