Hi DianeBustamante-7877,
Based on this SO thread you need to check your Dockerfile for exposed ports. Also setting explicit WEBSITES_PORT in your Azure Web App's "Application Settings" should help.
please see this detailed doc for addtional info: https://blogs.msdn.microsoft.com/waws/2017/09/08/things-you-should-know-web-apps-and-linux/#NoPing