Draw multiple line using abstract class

I checked your project and noticed that you are trying to draw Lines and Rectangles graphical objects on mouse clicks (using MouseDown and MouseUp events). I modified your project to save all pairs of points (on MouseDown and MouseUp) inside an array of points, and then loop through these points inside the Form1_Paint event to draw a line between each pair of points.
I am attaching the modified project for your reference.
Also, I have created a new class named PointsForRect that can hold four points. You can use these points to pass the required values to the this.CreateGraphics().DrawRectangle method to draw rectangles.

However, if you are looking for creating and drawing lines, rectangles, and different shapes on images, you can try more advanced options by trying the Annotations features from LEADTOOLS development SDK. You can find more details in this forum post I made:
https://support.leadtools.com/SupportPortal/CS/forums/44616/ShowPost.aspx

Disclaimer: I work for LEAD.