Accessing my AWS Lightsail Container Image Files

I am running container on lightsail service. I pulled it as a ready image from my container "dockerhub". Thus, I can access my docker image from the "public domain" in my container. But I want to create username and password for this image application. Normally, I was able to create a username and password when using it locally on my own computer. But I have no idea how to access my image's files in container. Can you help me?