After setting up an account, select Favorites as shown below and click on add + sign. Select Heart icon to add contact into favorites list.
To remove someone from your Favorites list, tap on the contact under your Favorites section and then tap the Heart icon again to undo it.
1. To move message into starred folder select more action from top right corner and select star.
2. You can also change the left/right swipe action to ‘Star’ and swipe left/right respectively to star an email.