Hello World is an example mod, shown in the Modding Guide, located here: github.com/WaywardGame/types/wiki
git clone https://github.com/WaywardGame/helloworld.git
cd helloworld
On Windows: path/to/wayward/install/wayward.cmd +mod update .
On macOS: path/to/wayward/install/Wayward.app/Contents/MacOS/Electron +mod update .
On Linux: path/to/wayward/install/wayward +mod update .