How to implement Polymorphism

public interface GraphicsObject
    {
        int Width { get; set; }
        int Height { get; set; }

        int Repetation { get; set; }
        int RepetationMin { get; set; }
        int RepetationMax { get; set; }
        bool IsRepetationRandom { get; set; }

        bool IsTop { get; set; }
        bool IsBtm { get; set; }
        bool IsOffset { get; set; }

        LineType LineType { get; set; }
        bool IsLineTypeRandom { get; set; }

        Shapes Shapes { get; set; }
        bool IsShapesRandom { get; set; }

        GraphicsPath[] Draw();
    }

public class FallingLines : GraphicsObject
    {
        #region Properties
        public int Width { get; set; }
        public int Height { get; set; }

        public int Repetation { get; set; }
        public int RepetationMax { get; set; }
        public int RepetationMin { get; set; }
        public bool IsRepetationRandom { get; set; }

        public bool IsTop { get; set; }
        public bool IsBtm { get; set; }
        public bool IsOffset { get; set; }

        public LineType LineType { get; set; }
        public bool IsLineTypeRandom { get; set; }
        #endregion

        #region Constructor
        public FallingLines(int width, int height)
        {
            this.Width = width;
            this.Height = height;

            this.Repetation = 10;
            this.RepetationMin = 8;
            this.RepetationMax = 10;
            this.IsRepetationRandom = true;

            this.IsTop = true;
            this.IsBtm = false;
            this.IsOffset = true;

            this.LineType = GraphicalDesigns.LineType.Irregular;
            this.IsLineTypeRandom = false;
        }
        #endregion

        #region Function
        public GraphicsPath[] Draw()
        {
            // does some work
        }

        private Rectangle[] GetRectangle(int randomOffset)
        {
            // does some work
        }

        private GraphicsPath GetPath(int x, int y, int width, int height)
        {
            // does some work
        }

        private Point[] GetPoints(int count)
        {
            // does some work
        }

        private Point[] DrawWave(Point top, Point btm, int cntWave)
        {
            // does some work
        }

        private GraphicsPath DrawIrregularity(Point[] points, int width)
        {
            // does some work
        }

        private Point[] GetRandomPointInLine(Point[] points, int curveCnt)
        {
            // does some work
        }

        private Point[] DrawIrregularWave(Point top, Point btm, int width)
        {
            // does some work
		}
    }

    public enum LineType
    {
        Straight,
        SineCurve,
        Irregular
    }

public class GeometricalShapes : GraphicsObject
    {
        #region Properties
        public int Width { get; set; }
        public int Height { get; set; }

        public int Repetation { get; set; }
        public int RepetationMax { get; set; }
        public int RepetationMin { get; set; }
        public bool IsRepetationRandom { get; set; }

        public bool IsOffset { get; set; }
        
        public Shapes Shapes { get; set; }
        public bool IsShapesRandom { get; set; }
        #endregion

        public GeometricalShapes(int width, int height) 
        {
            this.Width = width;
            this.Height = height;

            this.Repetation = 6;
            this.RepetationMax = 10;
            this.RepetationMin = 4;
            this.IsRepetationRandom = true;

            this.IsOffset = true;

            this.Shapes = GraphicalDesigns.Shapes.Circle;
            this.IsShapesRandom = true;
        }

        public GraphicsPath[] Draw()
        {
            // some work is done
        }
        
        private int[] GetIncBoxSize(int repetation)
        {
            // some work is done
        }

        private GraphicsPath GetPath(int x, int y, int wt, int ht)
        {
            // some work is done
        }
    }

    public enum Shapes
    {
        Triangle,
        Square,
        Rectangle,
        Circle,
        Oval,
        Pentagon,
        Hexagon,
        Octagon
    }

private GraphicsPath[] gPath = null;
        public GraphicsPath[] GPath 
        {
            get { return this.gPath; }
        }

        private PointF[] points = null;
        public PointF[] Points 
        {
            get { return points; }
        }

        public GraphicsMode mode; 

        public int Width { get; set; }
        public int Height { get; set; }

        public int Repetation { get; set; }
        public int RepetationMin { get; set; }
        public int RepetationMax { get; set; }
        public bool IsRepetationRandom { get; set; }

        public bool IsTop { get; set; }
        public bool IsBtm { get; set; }
        public bool IsOffset { get; set; }

        public LineType LineType { get; set; }
        public bool IsLineTypeRandom { get; set; }

        public Shapes Shapes { get; set; }
        public bool IsShapesRandom { get; set; }

        public GraphicsObject gObject;

        public ModelGraphics(int width, int height) 
        {
            this.Width = width;
            this.Height = height;
        }

        public void SetGraphicalObject(GraphicsMode mode)
        {
            this.mode = mode;

            switch (mode)
            {
                case GraphicsMode.GeometricalShape:
                    gObject = new GeometricalShapes(this.Width,this.Height);
                    this.Repetation = gObject.Repetation;
                    this.RepetationMax = gObject.RepetationMax;
                    this.RepetationMin = gObject.RepetationMin;
                    this.IsRepetationRandom = gObject.IsRepetationRandom;
                    this.IsOffset = gObject.IsOffset;
                    this.Shapes = gObject.Shapes;
                    this.IsShapesRandom = gObject.IsShapesRandom;
                    break;

                case GraphicsMode.FallingLine:
                    gObject = new FallingLines(this.Width,this.Height);
                    this.Repetation = gObject.Repetation;
                    this.RepetationMax = gObject.RepetationMax;
                    this.RepetationMin = gObject.RepetationMin;
                    this.IsRepetationRandom = gObject.IsRepetationRandom;
                    this.IsTop = gObject.IsTop;
                    this.IsBtm = gObject.IsBtm;
                    this.IsOffset = gObject.IsOffset;
                    this.LineType = gObject.LineType;
                    this.IsLineTypeRandom = gObject.IsLineTypeRandom;
                    break;
            }
        }

        public void GetGraphicalObject()
        {
            gPath = (GraphicsPath[])gObject.Draw().Clone();
        }