Failed to install java 7

As you can see from https://wiki.ubuntu.com/Releases Ubuntu 11.04 Natty Narwhal is declared End of Live since October 28, 2012

You need to upgrade to a supported Ubuntu release e.g. Ubuntu 12.04 LTS or 13.04.

I can upgrade directly to Ubuntu 12.04 LTS
or 13.04. or I have to start with Ubuntu 11.10? It tells me that the 11.10 will no longer receive important updates and support.
And if I can upgrade from Ubuntu 12.04 LTS Where I can do the download?

You can do upgrades in Ubuntu only from version to version (i.e. 11.04 -> 11.10 -> 12.04), or from LTS to LTS release (10.04 -> 12.04).

So you have two options:

1. Do an upgrade to 11.10 which is also already End of live (due to that fact, you have to use some specific tricks!), and then do an upgrade do 12.04.

2. Create backups of all your important files and do a new installation of 12.04 LTS.
You can download the installation medium from http://www.ubuntu.com/download/desktop (just use the approriate selections on that page).

That make copies of important files I get a little scared, because what those files are. So I think I'll update from 11.04 onwards, I do not want to spoil the computer doing things I can not do. I will not have any problems because the update has expired? I mean the NEXT version of mine. I'm sorry, but I'm a little lost.
Thank you.

There is a slightly outdated instruction https://help.ubuntu.com/community/EOLUpgrades listing pros and cons of upgrading vs. new installation, and giving also hints how to do the upgride if the versions are already EOL (changing repository server to old-releases.ubuntu.com).

I upgraded to 12.04 LTS and I still can not update java. The instructions tell me that I have to extract the downloaded file in the startup folder, but do not know what that folder. I've extracted in my home folder and do this in the terminal sudo mv java-7-oracle / / usr / lib / jvm / I get a message saying this: mv: can not stat `make 'on' java-7 -oracle ': No such file or directory
mv: '/' and '/' are the same file
mv: '/' and '/' are the same file
mv: can not move 'usr' to '/ usr': Directory not empty
mv: '/' and '/' are the same file
mv: can not move "lib" to "/ lib": The directory is not empty
mv: '/' and '/' are the same file

It seems that you mis typed the command, I guess there were extra space characters (/ usr / lib instead of /usr/lib etc.)

You could have installed openjdk-7-jre from the standard Ubuntu package sources without the need for complicated manual commands.

Please, I could say as I install it from the ubuntu package?

In the Ubuntu software center Open Executable see one java JDK 7
Is this the one that I have to install?

Corrected problems upgrading to version 12.04 LTS and I have installed java 7 without problems
Thanks for your help.