Installing latest Ubuntu on my desktop

I wish to install the latest ubuntu on my desktop. How do I go about doing this ?
Also how do I create the superuser or admin once the installation is done ?

To answer your second question first, the superuser account is the account that is created during install. The answer to the first question depends on what you would like the end result to be. Do you want to only boot Ubuntu or dual boot?

I'm having a problem installing Ubuntu over Linux mint. I was using mint and it just froze. So I held power button to turn off the computer. Turned it back on and it won't boot past the LM symbol. So I'm trying to install Ubuntu over it and erase mint but it won't let me. It says the hdd is mounted as /CDROM so I can't edit any files. Any ideas or ideas I can try? Can I make a bootable sun then boot from that, unmount the hdd, then format the hdd then reinstall Ubuntu? If do how do I do that? I tried unmounting it and it didn't work but I'm not very fluent with terminal commands and such.

When I ran diag on the boot up I did see a couple failures- media manager and something about a modem or network.

Any help at all would be greatly appreciated. Thank you in advance.

Try going into bios and erasing your hd. The set-up from vanilla.