There are iray presets in the "shader presets" in DS that will set a glow on a material zone. You would need to select the object and the material zone you want to glow on the surface tab in DS, then doubleclick the emissive shader preset. You can then select a jpg for the image you wish to glow and play with the settings for the glow amount. DZfire at the DAZ store also has some iray presets that do most of the work for you, but as Razor42 mentioned you could do a google search for how to do this for more information.