Notice that the curve shifts to the left as you raise the temperature. Basically this means that the star will have an increasingly bluish color as its temperature rises. Experimenting, you should find that red stars run around 2,000 K, yellow stars around 5,000 K, and blue stars around 7,000 K.
Our Sun runs a surface temperature of about 5,700 K, and appears light yellow. The very hottest stars run surface temperatures around 15,000 K. Keep in mind that the hotter a star runs, the shorter is its lifetime.
Stefan's Law, which is given in your book, uses the temperature determined by Wien's Displacement Law to find the true overall intensity, or luminosity of the star. From that information, it is possible to determine how far the star is away from Earth.
If you click here, you can try out an animation illustrating this law. You can raise or lower the temperature of the star (given in degrees Kelvin, or K), and the shape of the curve will change, with the most popular wavelength being the one corresponding to the top of the curve (greatest intensity).
The important point of this curve is that there is a most popular wavelength, a brightest wavelength. This brightest wavelength is related to the temperature of the surface of the star, not the star's chemical composition. The relationship between brightest wavelength and temperature is called Wien's Displacement Law, and can be found in your textbook.
Assuming that a star acts like a so-called blackbody (that is to say a very good absorber of incident radiation), which is a reasonable assumption, then the star should exhibit a radiation curve like that shown to the left. This curve shows the intensity of radiation as a function of wavelength.
There are two laws of physics that astronomers use that involve the temperature of a star: Wien's Displacement Law and Stefan's Law (also known as the Stefan-Boltzmann Law).