You need to set up initial position x(0), velocity v(0) and acceleration a(0)
and how the acceleration were changed at different time interval so that the simulation result will match the disgram already shown.
Press "play" to watch the simulation runs according to your setting and compare it with the default diagram to see if they match.
If you press "redraw xvt", the default x(t)/v(t) will be changed according to the setting,
and the values in the textfield will be reset to zero for another one to try!