docker container run hellowold
This is v2

docker image tag hellowold:2 prateekaxyz/hellowold:latest

 docker login http://hub.docker.com --username=prateek512
Password:
Login Succeeded

docker push prateekaxyz/hellowold:latest
The push refers to a repository [docker.io/prateekaxyz/hellowold]
93351e248e6e: Preparing
298c3bb2664f: Preparing
73046094a9b8: Preparing
denied: requested access to the resource is denied