Ah the comma used to separate sentences such as:
"The table is immaculate, and beautiful".
"I like my clothes to be tidy, and freshly washed".
You can also use the comma for separating lists and when you end a list, you must end it with a "And", for example: "Please bring back: apples, pears, bread and laundry detergent".
You also should use the comma for responding such as:
"Mr Peterson, please hire a new informant for the company".
You can also use commas as a way of separating a true or false question such as:
"hey peter you like pie, don't you?".
Or you can say "This wouldn't hurt, will it?".
When you are ending a dialogue sequence you have to put either a comma or full stop such as: Guillermo said, "The cave is very dark."
Or you can do: "It is probably clean," said Anne.