The Arduino IDE (Integrated Development Environment) is a graphics interface to a language based on C/C++. It is used extensively for programming a very wide variety of microcontrollers.
If you do not have the latest version of the Arduino IDE software, it is suggested you download and install the latest version.
The latest versions of the Arduino IDE have a library manager and board manager which are needed. It also has a new feature to switch between the ARduino USB Stack and the TinyUSB stack. for those reasons, using the WebUSB code should be used only on very recent IDE versions.
See the following pages on the steps to download the IDE and install it on your operating system.