I use igos nusantara linux in my old pc. Run well. But seems the igos that come from fedora, has a different update setting compare to ubuntu. It uses yum. So user modification repo should be add under /etc/yum.repos.d/

You can copy the structure from the existing repo file right there. But the simplest one must be written like this

name=yourfedora new repo
baseurl=http://www.new.com/pub/fedora/or/something/else
enabled=1
gpgcheck=1 //if any
gpgkey=file:///etc/pki/rpm-gpg/ifany

then save your repo file. finally do this as root:

#yum update