How can I move the vertices by clicking with the mouse?

please give me hint

This can be implemented using VTK widgets.

However, implementing applications with GUI and especially with 3D widgets is hard. As always, my recommendation is not to implement a new medical image computing application from scratch. If you need something very simple, go with a web application (e.g., based on OHIF/Cornerstone) because users will be upset it they have to install anything if all they need to do is to draw a box on an X-ray film). If you want to do some substantial processing and visualization then build on an existing medical image computing application framework (such as 3D Slicer or MITK).

See for example how markups work in 3D Slicer, implemented using VTK, ready to use in either C++ or Python: