How to bisect an angle

Take a compass and put the needle on the vertex.

make a mark with the compass that goes through both lines of the angle.

then with the 2 intersections that you just made, make 2 more marks from each intersection in between the 2 lines of the angle.

the 2 new marks that you just made should intersect.

now connect the vertex of the angle and the intersection you made in between the angle with a ruler