I'll take the liberty of quoting myself from an earlier thread:
# cat /etc/yum.repos.d/local.repo
[localrepo]
name=Fedora Local Repo
failovermethod=priority
baseurl=file:///Repo
enabled=1
#
You need to create the Repo directory, containing Packages [from the
DVD], and the repodata folder (from the DVD) in it.
This is quite a hassle. Do we consider this a feature that's not
needed enough to make it easier?