Yo, welcome to one of my very first and very old tutorials, a basic one.
As far as I'm concerned, it only works on both Photoshop 7, and Photoshop CS 8.

I'll try to explain it as super detailed as possible, so it'll be easy for you to understand.
Note: All results WILL be random.

Step 1:

Create a new document (CTRL+N) and, like in my case, make it 500 Width, 120 Height.
Then go to Filter>>Render>>Clouds.

You'll get this:



Step 2:

Go to Filter>>Render>>Different Clouds.

You'll get something like this.



Step 3:

Press CTRL+I and you'll get this:



Step 4:

Press CTRL+L and make it exactly like these settings:



Step 5:

You'll get something like this:



Now press CTRL+U and start coloring! Don't forget to check the "Colorize" box.



And the finish result will be something like this:



That'll be all, the tutorial is of course copyrighted by me, wich means NO STEALING!
Hope you enjoyed it , and that it was easy to follow enough.

^-^ Nice tutorial.

Thanks, I suppose it was easy to follow enough, it's also very cool o.o"