it works...

shaders/vertex.shader

@@ -7,16 +7,25 @@ uniform mat4 fg_ModelMatrix;
 //vertex-data
 in vec4 fg_Color;
 in vec3 fg_VertexIn;
-//in vec3 fg_Normal;
+in vec3 fg_NormalIn;
 
 //output-data for later stages
 smooth out vec4 fg_SmoothColor;
 
 void main()
 {
+   vec3 fg_Normal = fg_NormalIn; //vec3(0,1,0);
    //transform vec3 into vec4, setting w to 1
    vec4 fg_Vertex = vec4(fg_VertexIn, 1.0);
-   fg_SmoothColor = fg_Color;
-                    // + 0.001* fg_Normal.xyzx;
+   vec4 light = vec4(1.0,1.0,1.0,1.0);
+   vec4 dark  = vec4(0.0,0.0,0.0,1.0);
+   //direction to sun from origin
+   vec3 lightDir = normalize(vec3(5.0,5.0,1.0));
+   
+   
+   float costheta = dot(normalize(fg_Normal), lightDir);
+   float a = costheta * 0.5 + 0.5;
+   
+   fg_SmoothColor = fg_Color * mix(dark, light, a);// + 0.001* fg_Normal.xyzx;
    gl_Position = fg_ProjectionMatrix * fg_ModelMatrix * fg_Vertex;
 }