How it works
A comma is a tiny rest in the middle of a sentence. In a list it goes between the things: apples, bananas, grapes.
A full stop is a big stop at the very end of a sentence. A capital letter marks the start of the next sentence.
Type a comma straight after the word, with no space before it. Then tap the space bar once.
The right middle finger types the comma. The right ring finger types the full stop.