There are web sites and videos that stand ready to show you how to bisect an angle.
The basic idea is that you draw an arc through both rays so that the points of intersection are the same distance from the vertex. Then, you construct a perpendicular bisector of the segment between those intersection points. That will bisect the angle.
For (3), you bisect each of the angles made by the original bisector. (1/2 of 1/2 = 1/4)