You can copy/paste the script install.sh from here, or you can use:
git clone https://github.com/wbuchanan/elkStackInstaller
chmod +x elkStackInstaller/install.sh && sudo elkStackInstaller/install.sh
You can find the most up to date information about the ELK stack at : http://www.elastic.co.
To clone the repository (this should make it easier if there are future updates for you to keep things in sync on your system while having some form of version control available)