How to Make a Glow Brush
- 1). Click "Layer," then choose "New" and "Layer" to create a new layer. Click and drag the layer in the Layers window so that it is above your background layers if necessary.
- 2). Right-click the new layer and choose "Blending Options." In the window that opens, check the box next to "Outer Glow" to enable the option, then click the square of color and choose a light blue or gray color.
- 3). Click the brush tool and select the type of brush you would like to use in the "Brush Options" section. A brush with tapered edges is recommended. Click the color palette and choose a white or light blue color.
- 4). Click and drag the pointer across the canvas to paint with the brush. The brush strokes will glow as if they are made of light.
Source...