Now, you'll see ray tracing in action demonstrated with three simple spheres:
Open up a new file.
Delete the default cube.
Press Shift+A. Create a UV Sphere from the Add Mesh menu.
In the 3D View Tool Shelf, go to the Object Tools subpanel, and set Shading: to Smooth.
Press Numpad 0 to get the Camera view.
Press Shift+D to make a copy. Move the new sphere to the right and release it next to the original.
In the Properties window, choose the Material button from the header. It's the ninth button from the left, with the chrome ball on it.
Click on the New button and set the color in the Diffuse subpanel to red.
Select the original sphere again.
Press Shift+D to make a copy. Move the new sphere next to the original one on the left.
In the Properties window, click on the New button and set the color in the Diffuse subpanel to blue.
Select the center sphere again.
In the Properties window click on the New button to create a new material.
In the Mirror subpanel, check...