Abstract lines background

Step 1:

Let's start out by creating a new file. I used a 550x900 pixels canvas set at 72dpi, and I filled my background with a black color. [Edit:] Go to Filter > Render > Clouds. Select black (#000000) for the first swatch and a dark blue (#002266) for the second swatch. (thanks lucy and crusado!)

Step 2:

Create a new layer set and name it 'Abstract Lines'. Now select the brush tool and set the size to 45 px soft brush. In a new layer paint a medium sized line with # 006C6A color shade as shown below.