Make a copy of the template above - this will put it into your own Google Drive.
Search for an image that will fit into a 1" X 1" or 2.5" X 2.5" space comfortably, or create your own in Google Draw.
Download the image to your Chromebook, save it to your Google Drive, or copy (right click or CTRL + C) the image.
Paste the image onto the template and format the image to fit into a 1"x1" square.
Use the circle in the bottom left corner to make sure that enough of your image will fit into the circle, as this will be the size when it gets cut out.
Make enough copies of the formatted image to fill the desired amount of squares on your template.
Print them and cut them out using the punches.
Make your buttons and enjoy!