You can make an already existing image glow by the using the picture editing software Photoshop cs. The glowing effect can be given to an image by using Lighting filter in the Photoshop.
The following the steps will teach you how to give a glow effect to an image:
1. Open the image that is to be given the glow effect in Photoshop.
2. Click Filter>Render>Lighting Effect to open Lighting effect dialog box.
3. In the dialog box change the Light type to 'Omni' and continue with the default setting that is in the dialog box. If you want you can check the other effects by changing these settings.
The figure given below shows the image after giving the glow effect.