Use quotation marks around the exact words of a speaker.
The three Billy Goats Gruff had eaten all of the grass on their side of the river. The littlest goat cried, "I am hungry!"
Introduce a quotation with a word like "said" or "asked" followed by a comma.
The medium-sized goat replied, "We're all hungry."
After the words of the speaker, place end punctuation (or a comma) inside the closing quotation mark.
The littlest goat declared, "There's lots of grass on the other side of the river."
"Ah, but a terrible troll lives under the bridge," the biggest goat pointed out.
"I'm not afraid of him," snorted the little goat, and off he went.