Eclipse Xtext is implemented in Java, so you must have a Java Runtime Environment installed in order to proceed.
There are two easy ways to get Xtext up and running. A pre-configured Eclipse distribution is available which has already all the necessary plug-ins installed. Alternatively, you can install Xtext into your existing Eclipse by means of the Eclipse update mechanism.
If you have no existing Eclipse installed, it is probably easier to choose a pre-configured Eclipse. Alternatively, you can go to http://www.eclipse.org and choose the Eclipse IDE for Java Developers. Find the download link that matches your platform and follow the installation instructions above to extract and launch Eclipse.
Note: Xtext relies on the Antlr generator library. Unfortunately, we cannot provide this library on the official Eclipse release update sites. Instead, Xtext will try to download it on demand. To avoid this, you can manually install the feature Xtext Antlr-2.0.0 from the itemis update site (http://download.itemis.de/updates/). The general installation procedures are not affected by this issue.