I am currently working on a Win32 program where I have a picture. Depending where they click on the picture, something will happen.I just loaded the picture on the window, but how do I make it so that my program can tell when a certain area on the picture on the window is clicked? Thanks in advance.

You have to capture mouse events, which will give you the x and y coordinates of the mouse. Then just test those coordinates against the area of the window you are interested in to see if the mouse clicked inside or outside the rectangle.