Since Oracle Java is not shipped with Debian based distributions due to licencing issues, you must setup it manually via PPA repositories.

apt-get install python-software-properties -y

add-apt-repository ppa:webupd8team/java

apt-get update

apt-get install oracle-java7-installer

After Java is installed, go to ElasticSearch download page and download deb package.

wget https://download.elasticsearch.org/elasticsearch/elasticsearch/elasticsearch-0.90.9.deb

dpkg -i elasticsearch-0.90.9.deb</p>

At this moment (Jan 2014) 0.90.9 is latest version of ElasticSearch. Thats it. You have ElasticSearch installed!