To win you must convert all of the white counters into black counters. To change the colour of a counter, click on it will the mouse. However, beware - when a counter changes colour, so do those above, below, left and right of it!!
The moves counter shows you how many moves you have made. When it turns red, it shows the minimum number of moves needed to change all the counters, When it turns grey, you have made more than the minimum number of moves needed.