Emit slider in Shaders tab make material glow. There is one other Emit button under Map To tab. Do you need a image map for this or what? What’s the difference?
The first affects to entire material; the second affects the material according to the selected texture.
Or, a quick example. It’s the same base material in all four spheres. Bottom right has no emit, top right has only emit (shaders), upper left has a texture with emit (map to) with the same value as the top right sphere, bottom left has a different texture with different emit (map to) and other map to settings.
All the textures used are procedural, though you could use an image instead.