Make sure you can run shadertest1.py and that you can see a filled green disk on the screen. The color green is being passed into the shader through the tint constant. Try different color values for this constant. Then open up shader1.sha and notice how the value is used in the vertex shader to assign a color to a vertex. Play with the color values inside the vertex shader and see how it affects the final render.

Open and run shadertest2.py and make sure that you can see a shaded sphere this time. Ambient, diffuse and specular colors are being passed to the shader as constants. You can play with these values. Also notice that the light node is passed to the shader as well. Open up shader2.sha and examine how these values are being used. The constant mpos_light is the model space position of the light that is being passed in. This position is used to calculate the Light Vector which is then used to find the angle between the surface and the light, which gives rise to a diffuse color attenuation value. The specular attenuation value is missing. Just like you needed the light position passed in to calculate the Light Vector, you'll need to pass in the camera position to calculate the View Vector, which will be needed to fin the specular attenuation value. Once you've gotten the View Vector, you need to calculate the Light Reflection Vector with this formula: R=norm(2N(N.L)-L) and then you can calculate the specular attenuation value as the dot product of R and V raised to some power like 6 (pow(x,y) raises x to the power of y). Try to make this specular lighting work in your shader.