Remove the glass from your frame and clean well using glass cleaner. Allow to dry completely and place on top of a non-flammable work surface, like a cookie sheet. Use something to raise the glass off of the metal, like the frame itself (backside up).
Apply drops of alcohol ink to the glass surface. Pick up the glass and move around so that the colors merge and bleed into one another. You want to cover as much of the glass as you can in ink.
Add a small drip of rubbing alcohol and move the glass so that the ink spread to cover as much surface as possible.
Using a long utility lighter carefully light the ink and alcohol. Allow the flame to go out.
Repeat adding ink, alcohol and flame until you're happy with the design. Allow the glass to cool complete and place back into its frame.