variable save files/ user editing output

[ui uiho]

i was told recreate a version of dreamweaver(very basic version) and im trying to get the user to enter in the name of the file they want and im not sure how to do this. i also need to be able to output the info in a file and allow the user to edit the text within the program. any ideas on how to do this or anyone know any tutorials or walk-through to do this. i know how to do the files and uploading and appending files, i just do not know the concept of how to keep the text editable or to have a variable save file name.
EDIT: i found out how to save variable file names

  void savethefile(std::string fileinfo[]){
        std::cout << "Please enter the file name: ";
        std::cin >> filename;
        filename += ".html";
        savefile.open(filename.c_str());
        for(int i = 0; i < fileinfo->length(); i++){
            savefile << fileinfo[i]; 
        }
        savefile.close(); 
        std::cout << "File has been saved."; 
    }

i just need to know how to allow people to edit the outputted strings