Qt is a library not a language. Qt is written in C++ and designed to be used from C++ programs (although there are bindings for Python). All you require is a knowledge of C++ to learn how to use the Qt library. There are plenty of tutorials, examples and demos in the Qt documentation. That documentation is installed with the Qt library: run "assistant" or look at the Help in Qt Creator (if you have that).

Your program is not designed for a GUI, whether it is Qt or any other kind, so you will need to think about how your GUI program should work.

(I also suspect your program does not do what you expect)