Adding numbers in Google Sheets is a very simple process. You can either type the numbers into the cells yourself, or you can use the SUM function to add them together automatically. To type the numbers into the cells yourself, just click in the cell and start typing. To use the SUM function, highlight the cells that contain the numbers you want to add, and then click the "SUM" button in the toolbar. Google Sheets will automatically add the numbers together for you.