I have no idea what the creator of this example was thinking. Double commas? And at the beginnings of the sentences? WTF?
Get rid of the weird double commas. Burn them if you have to. 🙂
Then get rid of the em-dash before the second line of dialogue. (Yes, I know that’s done sometimes in subtitles on movies or television when more than one character is speaking in the same shot, but it’s not correct to do it in normal prose. If you insist on learning how to write from watching television, there’s nothing I can do to help you.) Dashes don’t belong in dialogue except to show an interruption or an abrupt change of idea within what one character is saying.
“It’s just… I saw her!”
“You know she’s dead.”