Warning message – help!

Hi there, I may have done a doozey and accidentally deleted or removed something I shouldn’t have 🙁 Can someone advise me on how I would go about adding it and where…I am a brand new user and do apologize if this is a ridiculous question!

The warning message populates every time I am in the “Customize” section.

http://www.beautyechoesmagazine.com

Please see attachment for a screenshot.