Placing a dot and a line segment on a graph

Hi, I'd love to get some help on drawling a dot (or a filled in circle) at (126, 0) and a line segment starting at (126,0) and ending at (232.8,0) in the graph below.
Array


Here's the code I'm using to generate the graph.

Code:

#delimit ;
graph twoway (function y=normalden(x,0,58.2), range(-232.8 232.8) lw(medthick)  ) ||
             (function y=normalden(x,-29.1,58.2), range(-232.8 232.8) lcolor(gs12)) ||
             (function y=normalden(x,-58.2,58.2), range(-232.8 232.8) lcolor(gs12)) ,
  //title("Sampling distribution of difference in sample means")
  xtitle("Difference in sample means")
  xlabel(-232.8(58.2) 232.8)
  ylabel("",nogrid)
  yscale(off)
  xscale(lw(medthick))
  xscale(titlegap(5))
  yscale(lw(medthick))
  legend(off)
  graphregion(fcolor(white));
#delimit cr

Thank you!