what's the command to conduct an upgrade from esx4.1 to esxi5.1?

    Basically, I copied 5.1 U1 ISO file to the host's /tmp folder, and renamed it to v51.iso. the host is running ESX4.1.

    I then mounted the ISO file to /mnt/cdrom successfully.

        I can go into cdrom and ls the content(see attached screen shot). now, what command do I use to start upgrade process?

    thank you in advance