This web page shows step by step how to easily install Java.
Let's first check whether Java is already installed on your computer. Type:
$ java -version java version "1.7.0_21" Java(TM) SE Runtime Environment (build 1.7.0_21-b11) Java HotSpot(TM) 64-Bit Server VM (build 23.21-b01, mixed mode)
If you see something similar it means that Java is installed properly. You can skip the rest of this web page.
TODO write how to actually install Java