what advice does cinna give katniss for her interview?

He tells her to "Be yourself, and pretend you are talking to me."

Cinna advises Katniss to be at ease and pretend that she is talking to a friend like him(Cinna). He also tells her that she should act like herself and hinted that there was no need to act as someone arrogant, charming, witty or even humorous. He told her to be honest and reminded her that the audience loved her no matter what and she should feel free to say anything that she likes even if it might leave a bad impression because in the end all of this may not really matter.

Be yourself, act like your talking to me.

what does katniss do to peeta at the end the chapter and why?