Get Java
Java is a programming language and free computing platform. It is the underlying technology that powers state-of-the-art solutions, like Liferay Portal. While portal works with Java version 5, it is recommended to use the latest version, Java 6.
If you do not have Java installed in your environment; don't worry! Portal bundle archive comes with Java and you will be able to run and use the portal.
Alternatively, you may download and install Java in your environment by yourself. Visit http://java.com and choose the Java installation according to your operating system. Just follow the online instructions and verify if the Java has been successfully installed.
Note: If you plan to modify and customize the portal, you will need the
Java Development Kit (JDK) installed. It is an enhanced version of the
Java Environment, used for developing new Java technology, available at
http://oracle.com/javase.
Download Portal Bundle
Let's download Liferay! Using your browser, go to http://liferay.com and click on ‘Downloads' in the top menu (or simply navigate directly to: http://www.liferay.com/downloads).
Liferay Portal is a Java web application; therefore it may run only on a Java system that supports web applications, such as an Application Server or Servlet Container. Portal works on most open-source application servers (Tomcat, JBoss, Jetty, and others), as well as on the commercial solutions (Websphere, Weblogic, and others). On the download page you can choose which Liferay portal bundle to download.

For starters, it is recommended to choose Liferay portal ‘Bundled with Tomcat'. Click on the ‘Download' button and wait until the download is complete.
Run Liferay Portal
Extract downloaded bundle into some folder, e.g. ‘portal'.
Navigate to: /portal/liferay-{version}/tomcat-{version}/bin
Execute startup.bat (on windows) or startup.sh (on Unix/lLinux/Mac OS X).
On windows systems the server console window will open. On *nix systems and others, there is no output in console window as all logs are stored in tomcat-{version}/logs/catalina.out. Keep watching it until (30-60 seconds on modern computers) you see something like:
INFO: Server startup in NNN ms
Liferay Portal is now up and ready. Upon start, the portal URL address (http://localhost:8080) will automatically be opened in your default browser.

Congratulations, you are now running Liferay Portal!
You can sign in using default user: test@liferay.com and password: test.
Next Steps
CHANGE DATABASE
The Liferay Portal bundle uses an embedded database to make installation fast and easy. This database is not ready for production so consider configuring Liferay to use a production-ready database available to you (MySQL, Oracle, etc).
http://www.liferay.com/community/wiki/-/wiki/Main/Database+Configuration
CONFIGURE EMAIL NOTIFICATIONS
http://www.liferay.com/community/wiki/-/wiki/Main/SMTP+Setup
READ OFFICIAL DOCUMENTATION
http://www.liferay.com/documentation
LEARN MORE ON OUR WIKI
http://wiki.liferay.com
ASK QUESTIONS ON OUR FORUM
http://forum.liferay.com
GET PROFESSIONAL SUPPORT
http://www.liferay.com/services