Elementary OS (or Jupiter) needs to be installed like any other OS: you burn a CD.
Click the link and choose download or click these links for the i386 or for the amd64.
How can I install Jupiter?
Simply burn the iso to a CD, or install it to a flash drive. Insert the CD or flash drive into your computer, then reboot and you should see the elementary installer which will guide you through the installation. If your computer won't boot to the CD or flash drive, you may need to change the related option in your computer's BIOS.
Default apps:
Midori web browser
Docky
Dexter Contacts app
Postler e-mail client
Lingo dictionary
Abiword word processor
GNUmeric spreadsheet app
Software Centre
Shotwell
Totem Movie Player
Empathy
Nautilus-Elementary
Warning regarding Natty: "… users of elementary OS Jupiter may be prompted to upgrade to Ubuntu 11.04. We strongly urge you not to do so [...] because the upgrade process may render your install unusable."
From omgubuntu
If you need this OS inside Ubuntu you can
Add Virtualbox and install Elementary OS inside virtualbox.
Create empty space on your hard disc (so a 3rd partition: ubuntu, windows, elementary) and triple boot.
Ubuntu 11.04 does not play nice with this OS. If you want 1 Ubuntu with elementary OS in it you need to use Ubuntu 10.10.
Rinzwind's thorough answer is how you can get a stable 0.1 release of ElementaryOS that is based off of 10.10.
If you want to convert your 11.04 installation into a beta build of ElementaryOS, then the following steps will do that for you:
WARNING: It is NOT advised to do this with anything but a clean installation of Natty.
Second Warning: This might not work for you at all since it is beta software. This WILL erase everything in your ~/Desktop folder. You WILL have to create a new user after this to complete the process. You have been warned.
Last chance to back out here.
If you're sure you want to transform your Ubuntu 11.04 install into Elementary OS then run the last command:
sudo conf.sh --configure-installed
After this is done (it takes a while) create a new user in the Users Settings application. Restart your machine (logging out might work, but I would advise doing a full restart). I'm not 100% sure if you will have to log in to the new users account, but it seems likely.
For 12.04 (stable) only:
Use the following PPA:
For 12.04, 13.04, and 13.10 (unstable, daily updates):
Use the following PPA:
Then update and install the elementary-desktop package.
To login to your new eOS desktop, logout, and choose Pantheon as your session.
Optional extras:
Apps such as Birdie and Agenda can be found in another PPA:
As complete as I can make it:
Elementary OS (or Jupiter) needs to be installed like any other OS: you burn a CD. Click the link and choose download or click these links for the i386 or for the amd64.
From their FAQ:
Default apps:
Warning regarding Natty: "… users of elementary OS Jupiter may be prompted to upgrade to Ubuntu 11.04. We strongly urge you not to do so [...] because the upgrade process may render your install unusable."
From omgubuntu
If you need this OS inside Ubuntu you can
Rinzwind's thorough answer is how you can get a stable 0.1 release of ElementaryOS that is based off of 10.10.
If you want to convert your 11.04 installation into a beta build of ElementaryOS, then the following steps will do that for you:
WARNING: It is NOT advised to do this with anything but a clean installation of Natty.
Second Warning: This might not work for you at all since it is beta software. This WILL erase everything in your ~/Desktop folder. You WILL have to create a new user after this to complete the process. You have been warned.
In a terminal one after another:
Last chance to back out here. If you're sure you want to transform your Ubuntu 11.04 install into Elementary OS then run the last command:
After this is done (it takes a while) create a new user in the Users Settings application. Restart your machine (logging out might work, but I would advise doing a full restart). I'm not 100% sure if you will have to log in to the new users account, but it seems likely.