When quoting someone put parenthesis at the beginning and end of the sentence. Ex) "Almost all RadioShack's are closing nationwide" said Mr. Smith.
The punctuation mark at the end of the sentence goes inside the parenthesis at the end. Ex) "Almost all RadioShack's are closing nationwide."
You can also use a phrase like, according to, when starting a quote.
Ex) According to Mr. Smith, "almost all RadioShack's are closing nationwide."