The text editor is in the left for writing your code and there is an output in the right.
You can load example programs by selecting from the dropdown in the top right and clicking "Load Example".
You can run your program and stop it, as well as clear the terminal, by clicking the buttons in the top left corner.
The "Auto-clear" option clears the terminal before every run of your code.
You can also upload and download your code with the buttons in the upper right corner.
You can find detailed syntax documentation on GitHub here.
But for now, feel free to try out the examples.
There is! You can install backwash for the terminal with npm.
Just run npm install backwash-lang.