One of the things that make image editing apps exciting to use is the constant thrill of stumbling upon something unexpected, but produces interesting results.
One such thing is Adobe® Fireworks®’ Satin Gradient, and how its (kinda) unpredictable behavior makes it easy to create abstract glowing light swirls with.
This’ll be a breeze…
Start with a white canvas, and create a rectangle using the Rectangle Tool 
. Give it a Satin gradient of one color going from 0% to 100% opacity. Take this opportunity to play around with the gradient handle. Different angles and lengths produce different curves. (I’m assuming it’s based on a complex algorithm that only a rockstar mathematician would appreciate.)
Figure 1. Rectangle with a Satin gradient.
With the rectangle still selected, clone it (Ctrl+Shift+D), and give the new rectangle a different color (while keeping the opacity) and gradient direction. You’ll begin to see the blending effect created by the gradient and opacity.
Figure 2. Another rectangle with a Satin gradient.
Repeat the last step one more time to get more variety into the colors. Then, keep experimenting with the colors and the gradient direction until you get desirable results. You can also play around with other things as layer opacity and blending for greater variety.
Figure 3. Yet another rectangle with a Satin gradient.
Below are a few more samples of the variety you can create with just 3 rectangles and satin gradients:
Source: http://www.brownbatterystudios.com
