c++ windows gui change button colors : I wanna change button colors when the user click on it.
The main plan is: every month 10th one worker's button go to red and if the worker done his job then click on the button and it going to be green.
I have no idea what to do.
I already have this code... I just created a window and add a button to it:

    #include <windows.h>
    
    LRESULT CALLBACK WindowProcedure(HWND,UINT,WPARAM,LPARAM);
    
    void AddButton(HWND hwnd);
    
    
    LRESULT CALLBACK WindowProcedure(HWND hWnd, UINT msg, WPARAM wp,
    	LPARAM lp)
    {
    	switch (msg) {
    	case WM_DESTROY:
    		PostQuitMessage(0);
    		break;
    	case WM_CREATE:
    		AddButton(hWnd);
    		break;
    	default:
    		return DefWindowProcW(hWnd, msg, wp, lp);
    	}
    }
    
    void AddButton(HWND hWnd)
    {
    	CreateWindowW(L"Button", L"Change colors", WS_VISIBLE | WS_CHILD,
    		350, 200,
    		100, 100,
    		hWnd,
    		NULL,
    		NULL,
    		NULL);
    }

So I tried WM_LBUTTONDOWN... I think this is something when the user click on the button the program will do something. i put in the switch(msg) case WM_LBUTTONDOWN:
but no idea what's next 