How can I draw a picture

I assume you're asking not about static picture but about drawing during run-time.

You should use overridden method System.Windows.Forms.Control.OnPaint or handle event Control.OnPaint; in both case use the instance of the class System.Drawing.Graphics passed in event arguments in both cases. The control can be a System.Windows.Forms.Form or any other control, such as System.Windows.Forms.Panel. You can do it in the custom control created by subclassing System.Windows.Forms.Control (typically).

Please pay attention: the common mistake is creating an instance of the class System.Drawing.Graphics using its constructor. You should not do it (as a rule of thumb); the instance is already provided in the arguments of the methods mentioned above.

If you need to modify the graphics (with is need for animation or just to reflect changed state. In this case, you need to changes the data you use for rendering and call Control.Invalidate. To improve performance, you can used overloaded Invalidate methods with parameters (Rectangle or Region) to invalidate just the part of the control. After invalidation, WM_PAINT Windows message will be triggered, which will cause the call of your rendering method OnPaint and then your handlers of Paint event if you provide any.

—SA