Visual C# Paint Application

Question

Hello. I am working on a GUI with multiple windows forms. On the click of a menu button a second form with a single picturebox appears. I want to click on a menu button on this form that will make a third form pop-up with paint like tools (color selection, brush width) to draw on the picturebox. So far, the picturebox will upload the picture and the form with the paint like tools will appear. Can someone help with the code to draw on the picturebox?