The height of the wave is called its amplitude. Sound waves are louder when the amplitude is higher. Light waves are brighter when the amplitude is higher. In the animation you can change the amplitude by typing a number between 2 and 90 and then clicking the Amplitude button.
Wavelength is the distance between successive peaks. There is a relationship between wavelength and frequency. The shorter the wavelength is, the higher the frequency and vice versa. For visible light, the blue end of the spectrum has the shortest wavelength and the highest frequency. At the other end of the spectrum, red light has the longest wavelength and the lowest frequency. You can read more about electromagnetic waves on the Electromagnetic spectrum page. Radio waves have longer wavelengths and lower frequencies than light waves, but they are essentially the same thing, ie electromagnetic waves. X-rays have much higher frequencies and shorter wavelengths than visible light.
For electromagnetic waves the wavelength is equal to the speed of light divided by the frequency of the wave.
Now you can experiment with adding sine waves together on my Phun Physics page.