Oscillating Spring

This applet simulates the motion of a spring having a ratio b of stiffness to mass. Motion is approximated by uniform acceleration over time intervals dt=0.07. The applet is a simplified version of "Harmonic oscillator - The Spring" by a.zampa.
Adjust the initial position, initial velocity and ratio of stiffness to mass. How do these coefficients affect amplitude, frequency and phase of oscillation?