IN GENERAL (since you did not attach the figure):
A. Name an angle with three letters, where the middle letter is the vertex of the angle, and the other two letter as the non-collinear points in the angle.
Example: ∠ABC; A and C are the non-collinear points, and B is the vertex and the common endpoints of Rays BA and BC (use the ray symbol drawn above the letters).
The angle is also named with a letter representing the vertex. In example above, ∠ABC can also be written as ∠B.
B. The minor arc is represent by the two letters representing two distinct non-collinear points of the angle that intercept the circle.
Example: arc MO (Use the arc symbol drawn above the letters)
The major arc is usually represented by three letters that, where the middle letter is the point between the two points that intercept the circle.
Example: arc MNO (use the arc symbol drawn above the letters)