Getting Error in subscription-manager register

I started learning Red Hat a couple of days back. As I'm new to this, getting a tough time to begin. I stated my situation below.

1) I installed Red Hat and I wasn't able to download any package using Yum install. The error i'm getting is "This system is not registered with an entitlement server. You can use subscription-manager to register.
There are no enabled repos".

2) When I try to subscribe, I was getting the error like "gaierror: [Errno -2] Name or service not known
[INFO] yum:32656:MainThread @connection.py:822 - Connection built: host=subscription.rhsm.redhat.com port=443 handler=/subscription=identity_cert ca_dir=/etc/rhsm/ca/ insecure=False
[INFO] yum:32656:MainThread @repolib.py:328 - repos updated: Repo updates

Total repo updates: 0"
Note: I used, subscripe-manager register --username name --password ****

Could anyone help me with the above error?