This widget is using a plugin called Genesis Latest Tweets from StudioPress. You may download it from the WordPress.org plugin repository.
Go to Genesis -> Latest Tweets
- Add necessary API settings provided by Twitter
- Save
To to Appearance -> Widgets
- Drag Genesis Latest Tweets over to your desired sidebar
- Input desired text in Title
- Input your Twitter handle (not full URL) in Twitter username
- Set desired number of tweets to show
- Save