Use Color Dodge to brighten your graphics.
Photoshop has many different ways of blending layers. Different blending modes determine how the pixels on one layer effect the pixels on other layers beneath it.

The NORMAL blending method simply filters the pixels on one layer onto the other layers, shifting the pixels closer to the top layer's color.

Different blending modes are available right under the LAYERS tab.

Color Dodge, depending on the opacity and lightness of the pixel, brightens and saturates the underlying pixels.

The NORMAL layer looks dull and de-saturated, while the COLOR DODGED layer whoops the monkey's ass.

The above pictures both have layers with COLOR DODGE blending. Blurring the layer makes a nice gradient from brightness to the background pixels. Use this effect to give your imagery a sweet GLOWING effect.