Cent OS Upgrade for third party distribution

have a distribution build from some Cloud company and this is built on CentOS. Usually i do upgrade from Browser by accessing Vami Portal. But i really want to know if i can do this from command line using 'yum'

the process i follow now is :

I extract build boot it using VMPlayer.
Assign static IP and configure network.
the go to vami portal using static ip throw Browser.
save repository path and do upgrade

Thanks