Program in C++

I need to code a program in C++ which would restrict access to an application(say Notepad) for particular users.

For example, Let us  consider 2 users A and B. A is authorized to access the application whereas B is not authorized to access the application.Whenever user B double clicks on the application,It should give a popup saying "You are not authorized to access the application".How can I code this scenario in C++ ? Please help me out.