I copied the code into a Google gadget using the editor here: Gadget Editor
I saved the gadget with a new name and then copied its URL.
Back on this page I clicked Insert and selected More gadgets.
I selected Add gadget by URL and inserted its URL and clicked Add.
I set the width to 100% and height to 600 pixels. You might want to experiment with the settings.
Another method is to create a page and host it in a public Google Drive folder. Embed that page using an iFrame gadget. Example here and Instructions here.