Below thumbnails or post date? for post date you can alter it from Appearance > Theme Options > Hide Page Top Meta: OFF.
You need to create menu first from Appearance > Menus.
Then, you can add navigation/menu on the left side under the title from Appearance > Customize > Navigation > Main Side Navigation & Side Navigation Bottom.
I’ve found out if you have a directory called feed (silly me) in the root directory of your website (public_html). It will cause your feed not working.
Deleting it will simply allow the script to run normally again.
