NOTE: I've listed 'redhat enterprise linux for real time' as the OS since I can't find an entry for standard Red Hat linux (7.4 beta)
In any case, I see that /etc/yum.repos.d to be empty except redhat.repo files which has no meaninful contents.

yum update - gives me this info

Loaded plugins: langpacks, product-id, search-disabled-repos, subscription-
: manager
This system is registered with an entitlement server, but is not receiving updates. You can use subscription-manager to assign subscriptions.
There are no enabled repos.
Run "yum repolist all" to see the repos you have.
To enable Red Hat Subscription Management repositories:
subscription-manager repos --enable
To enable custom repositories:
yum-config-manager --enable

--- Any of the commands above are not useful to me. I have used subscription-manager to register the product.
Can someone please help? After tiring to do update -really- i've chosen to create post here. Thanks in advance.
Ravi
PS : not sure if it's worth metioning, I am only trying out Redhat through their developer program - and am not a paying customer.
I've tried copying files yum.repos.d, but no avail.
Only I needed to try - which I haven' t yet - is to use server dvd as source of packages.