I decide to share this guide as java is not installed by default in Ubuntu 12.04 and the ones that replaces it like eclipse or openjdk don't let you install Multibit HD in this operating system.
Here is the link to the best guide which can help you install java in Ubuntu 12.04 and then follow the commands in multibit.org on how to install it on Linux.
I thought to share this to help some newbies who may have this operation system.
Link to the guide of installing Java in Ubuntu 12.04
http://www.krizna.com/ubuntu/how-to-install-oracle-java-7-on-ubuntu-12-04/
