how can i read/write in a textEditor ?

hi about an hour is i am seeking for a sipmle code or program that can read/write from texteditor in Qt. i want to read values or strings from text editor in GUI and show result of program on textEditor to user. Just like a console window . in fact i want to buid something like terminal with texteditor that i can get inputs from user in it and show the result to user again in it . :D