Installing MineOS involves numerous steps. These steps do not require that you have partitions or filesystems applied, as that is part of the setup process.
These steps cover both the x86 and x64 versions.
Logging in for the first time
If all went well, it should boot into Linux and look like this:
From here on, I encourage all users to connect to their Linux machines via PuTTY, which has countless advantages and is the industry standard way to connect to Linux machines remotely (even if you're working on the same machine).
See the PuTTY page for instructions on how to download, use, and improve your Linux experience with a terminal window instead of interacting with the machine directly.
As stated at the end of the setup process, you should use the user 'mc' for all minecraft-related management, including using the Web-ui, downloading the server jars and handling backups/archives.