Uncaught ReferenceError google is not defined (spreadsheet) on HTML?

I want to do a web page, with google spreadsheet as storage, and I need to upload some cells, just like this: [link]

But when I do that it give me this error "Uncaught ReferenceError: google is not defined" or "Uncaught ReferenceError: google is not defined at HTMLInputElement.onclick"

I assume I have to put some reference, but I do not know how I get it