1) The streams you see at the top are the features you have in your app. You need at least four streams to publish an app to the app store.
2) Click on the feature you'd like to add or activate.
3) Name your stream.
4) Upload your cover image if you're using the Perspective Layout, or if you're creating a collection.
5) Replace the default data with your own information by following the instructions specific to each feature. Click "Done" to preview on the right.