Here’s an example:

“As for the 1972 Dolphins, I don’t take joy in the fact the Patriots lost — period,” said Jim Mandich, the tight end on the 17-0 team. “But I do relish and savor the fact that there has only been one unbeaten team in the history of the NFL, and it is the 1972 Miami Dolphins.”

No, No, No, No. You don’t put “Period” on the end of a sentence just for extra emphasis, or as another way of saying “And I mean it!”. You put it there when you are shortening someone else’s sentence.

Example Of Correct Usage

“I think you don’t want to go to Iowa with Peter’s friends.”
“No, I don’t want to go to Iowa, period.”

You see? It’s not difficult. It’s just not very often that it is applicable. But using it improperly makes you look, to anyone with verbal awareness, like someone who is trying to sound impressive but is ignorant of how to do so.