Third-party software is required to edit QScript. There are two types of software that can serve this purpose: text editors and integrated development environments.
Text editors are programs designed for editing text. The most well-known is NotePad, which appears on most computers. More sophisticated text editors can be set up to automatically highlight QScript to make it easier to read. See Setting Up TextPad for instructions for one of the many text editors.
An even more powerful approach is to use and integrated development environment (IDE), which is a program specifically designed for writing code. This is better than a text editor as the programs are very 'smart' and will alert you to errors and opportunities for improving your code. See Setting Up WebStorm for instructions for one of the many IDEs.