MFC CRectTracker

Hi,

I am trying to develop a MFC application that lets a user upload a photo and display it, and then the user will select a rectangular region of this photo and get its coordinates in pixel values.
I am quite new to C++ (have mainly done C in the past) but I have managed to load and display the image, however I am a bit stuck on defining the region.

After some research I found that the CRectTracker Class probably will be able to achieve what I need, but I cannot seem to understand how it works from the Microsoft documentation provided.
As far as I can tell I need to use the CRectTracker::Track as the description says "Call this function to display the user interface for resizing the rectangle" but when I call it nothing happens (nothing appears on the application to suggest that I can resize any rectangle).

This is what I got so far, any help would be greatly appreciated.

Code:

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CRect rect2;
CPoint p;
CWnd* pWnd = GetDlgItem(IDC_PICTURE_CALIBRATION); //This is the ID of CStatic that is the photo displayed
pWnd->GetWindowRect(&rect2);
ScreenToClient(&rect2);
CRectTracker ROI = CRectTracker(rect2, CRectTracker::resizeOutside);
pScreenDC = GetDC();
//ROI.Draw(pScreenDC);
ROI.Track(pWnd, GetCursorPos(&p), FALSE, NULL);
ReleaseDC(pScreenDC);

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I never user this class and have no idea how and why should it be used.
however, you could start with the Microsoft sample Tracker

Thanks for the example.
I have now managed to get a resizable rectangle on my application but I am facing another problem which is that the rectangle is behind the image so it can't be seen. Is there any way of moving the CRectTracker object to the front?