how to plot a line with AFL

how can i plot a line between 2 selected points.

Code:

---

_SECTION_BEGIN("trendline");

var1=SelectedValue(O);
var2=SelectedValue(C);

_SECTION_END();

---

If i use

Code:

---

Plot(startpoint,"Low",colorYellow,styleLine,1);

---

it plots a straight line at the value of var1...i want to get a line from var1 to var2

how to plot a line with AFL