Amplitude is the maximum displacement of a particle from its equilibrium position.
If you imagine a straight line, x. With a wave along it, the amplitude is the distance between the line, and the peak of the wave.
The definition of frequency is the number of oscillations per unit time. The way I remember it is its the number of waves that pass a fixed place per whatever time so if you choose a point on the wave, it's the number of waves that pass over that point :)