Verified answer

first, you should use and open and close quotation mark before and after the quotation.

second, write the author's name

lastly, italicize the quote and the author's name.

so basically, it would look like this:

“A friend is one who walks in when others walk out." -- Walter Winchell

P.S.

It can't be italicized here... so, just italicize it in your Microsoft Word or whatever you Word use...