Rock the CD back and forth at an angle until you see a rainbow stripe in the disc. Closing one eye often helps. If you have a dimmer switch on your incandescent bulb, see what happens to the spectrum as you dim and brighten the bulb. When it's dim, the red end of the rainbow will be more prominent. When it's bright, the blue end of the rainbow will be more visible.
Stars are like the filament in the light bulb.
Their spectrum can tell you their temperature. Now use your CD to look at the light of a street lamp. Again, make sure the lamp is in the distance to your left and rock the CD in you right hand. When different gases glow, they glow with their own unique set of spectral colors. Download the Adobe Acrobat Reader to view them.