midpoint=(x1+x2/2 + y1+y2/2)
= (-1+3/2 + 2+6/2)
= (2/2 + 8/4)
midpoint= (1,2)
now you must find the slope of the line
slope= y2-y1/x2-x1
=6-2/3-(-1)
=4/4
=1
slope=1
now since its a right bisector it must be the negative reciprocal, therefore the slope of the line you want is -1
now simply plug the values into the equation of a line first putting it into the equation y- k = m(x - h)
then solve the point slope equation for y to get y=mx+b
can you finish it?