How to run programs with Qt\C++ interface?

Question

Qt

Okay, maybe a stupid question, but I didn't find the answer.
So: let's say I created a program in Qt, it has files:

main.cpp mainwindow.h mainwindow.ui Notebook.pro.user
mainwindow.cpp mainwindow.h.gch Notebook.pro

How do I run it? When I compile files with g++ I just get an error:

mainwindow.h:4:10: fatal error: QMainWindow: No such file or directory
#include QMainWindow

How do I run it with the interface on other PCs?
Added: let's imagine that I sent this program to a friend, he does not have qtcreator, but he wants to run a program with an interface on his PC, what should he do?

Answer 1

Added: let's imagine that I sent this program to a friend, he does not have qtcreator, but he wants to run a program with an interface on his PC, what should he do?

It needs to be compiled and delivered along with all libraries: https://evileg.com/en/post/163/

Answer 2

Use builders like qmake or cmake.

Answer 3

Notebook.pro is a QtCreator project. Download, install, open, explore.