After you've got your firmware set up and running, you should use the website to configure the chip:
First, get to know your board and which pins are usable.
Then, you can use the bottom section of the webpage to configure you inputs and outputs.
Once that is set up, just tap on the output buttons on the webpage and check if your LEDs on the board light up (if there are any).
Then, if there are buttons on the board and configured, you can press them and check if the input buttons on the webpage change color.