The VIATRA website describes where to download VIATRA from: https://www.eclipse.org/viatra/downloads.php This tutorial was written for version 1.4 (released on 30th September 2016).
VIATRA is available from the p2 repository at http://download.eclipse.org/viatra/updates/release
To install VIATRA, select the Help/Install New Software..., then paste the copied URL to the Work with field, than press Enter. When the view is updated, select the VIATRA Query and Transformation SDK. Tick the Contact all update sites during install... field. Press Next, then Next and finally Finish. After the install process, you should restart Eclipse.
For a faster installation, you may deselect the Contact all update sites during install... field, but then it is necessary to install the required Xtext SDK manually.
This tutorial relies on the CPS demonstrator example from https://git.eclipse.org/c/viatra/org.eclipse.viatra.examples.git/tree/cps (for a description of the example please consult https://github.com/viatra/viatra-docs/blob/master/cps/Home.adoc).
This document assumes that the metamodels themselves are installed into the Eclipse instance. They are available from the p2 repository https://build.incquerylabs.com/jenkins/job/CPS-Demonstrator/lastSuccessfulBuild/artifact/cps/releng/org.eclipse.viatra.examples.cps.update/target/repository/