Yum repo URL for Boot ISO installation

Hello,

Downloading the complete RHEL 7 Desktop DVD takes forever, so I went for the way lighter Boot ISO but...
There's no Installation Source configured so Installation won't go on and I'm stuck at the last screen with the "Begin installation" button disabled.

I need at least one valid URL for a proper RHEL 7 Desktop yum repository, so I can configured it and proceed with the installation.

Any hints? :)

Thanks,
William