MM, I'm not sure I remember how to post a chart... QQQ chart.
Where you see the red ticks, that would be equivalent to the Darvas upper Box line being exceeded and a new box developed.
So, if you bought at $50, the new boxes keep getting developed as the stock moves towards $120. Then as the price starts to move down, the lower box line is broken (the green + ) around $100 and the position would be closed out.
The reverse approach could be used as the stock moved downward.