I am trying to make an Image Editor in C++ (winapi). I've only done setting up the window and menus like File (consisting New, Open, Save, Exit). But I am completely clueless about how to load the image requested by the client, and how to let them draw over it and save it.
I don't think, the initial code matters here, That's why I'm not posting it. Let me know if you need it.
If you're using C++ and winapi then you should consider using the MFC framework. This provides pretty good wrappers for all the native windows graphics objects and actions; and, what I find especially useful is the "CImage" class. This has a "Load" member that, given a path to a file, can open an image in any of the 'standard' graphics formats (bitmap, GIF, JPEG and TIFF). Once open, you can use the class's functions like "BitBlt" to render the object's image to a View (window). You can also extract a 'handle' to the underlying BITMAP object (the actual array of pixel colours), and with that you can apply any changes the user makes to the displayed image.
I use this class extensively in one of my software projects, which has a large set of image-editing/-processing operations.
Sorry if this is a bit vague - but, then again, so is your question!