Apache Hadoop 2.10.2 is a point release in the 2.10.x release line, building upon the previous stable release 2.10.1.
Users are encouraged to read release notes for overview of the major changes and change log for list of all changes.
The Hadoop documentation includes the information you need to get started using Hadoop. Begin with the Single Node Setup which shows you how to set up a single-node Hadoop installation. Then move on to the Cluster Setup to learn how to set up a multi-node Hadoop installation.