How do you bisect an angle?

Take a compass. Open it so that it is a large enough radius to be easy to draw, but small enough that it still marks on both lines of the angle. Draw an arc that crosses both lines making up the angle, then place the point on each of these intersections and draw two more arcs of the same size so that they intersect. Using a straightedge, draw a line from the point of the angle to the intersection. That is the bisecting line.