Help needed on program that draws shapes

I'm working on some homework and need to create an application that draws 3 shapes when the form is clicked. The objects are suppose to be drawn on specified surface area within the form. I have the surface area being created but cannot seem to get a shape to be drawn onto it when clicked. I'm thinking that there is a problem with my event handling of the mouse click but I cannot seem to figure out how to fix it. I have included my code and would appreciate any help or direction that you guys could provide me.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace William_Cappoli_IT466_Unit_6_Project
{
    public partial class frmMain : Form
    {
        private DrawImage imgDraw;

       public frmMain()
        {
            imgDraw = new DrawImage();

            InitializeComponent();
        }

        protected override void OnPaint(PaintEventArgs paintEvnt)
        {
            // Get the graphics object
            Graphics gfx = paintEvnt.Graphics;
            // calls draw method from DrawImage class and passes it the graphics object
            imgDraw.DrawBoundingBox(gfx);
        }
       
        private void frmMain_Click(PaintEventArgs e)
        {
            Graphics imgObj = e.Graphics;
            imgDraw.Draw(imgObj);

        }

    } // end partial class frmMain class
}


using System;
using System.Windows.Forms;
using System.Drawing;
using System.Collections.Generic;
using System.Linq;
using System.Text;

    class DrawImage
    {
        // private members that determine where drawing surface starts, how big it is and the color of it
        private float xCoordinate = 0;
        private float yCoordinate = 60;
        private float width = 521;
        private float height = 560;
        private Color backcolor = Color.White;

        // creates surface for drawing objects onto
        public void DrawBoundingBox(Graphics g)
        {
            // Create a new pen that we shall use for drawing the line
            Pen myPen = new Pen(Color.Black);
            SolidBrush myBrush = new SolidBrush(backcolor);

            g.DrawRectangle(myPen, xCoordinate, yCoordinate, width, height);
            g.FillRectangle(myBrush, xCoordinate, yCoordinate, width, height);


        } // end DrawBoundingBox method

        // draws rectangle when form is clicked
        public void Draw(Graphics o)
        {
            Pen imgPen = new Pen(Color.Black);
            o.DrawRectangle(imgPen, 90, 100, 45, 75);
        }

    } //  end DrawImage class

Thanks in advance