You are an experienced programmer and have a problem with the engine, shaders, or advanced effects? Here you'll get answers. No questions about C++ programming or topics which are answered in the tutorials!
You can either export into a mesh format which supports vertex normals (AFAIK most of them do, only 3ds has a different way which is currently not supported in Irrlicht), or you use the mesh manipulator and do a recalculateNormals with smooth turned on.