From the error message, it is clear that either the image you are trying to pull is not present in DockerHub or you need to login into your DockerHub account.
- If image not present in DockerHub, first push your image into DockerHub, then only you can pull it.
$ docker push yourDockerHubAccountName/voting-app
$ docker pull voting-app
- Login into your DockerHub account:
docker login --username=yourHubUserName --email=yourRegisteredEmail@provider.com
You will be prompted for password on the bash screen. Enter your password to access all the public images ever uploaded on DockerHub.