Information on HDP 2.1 Manual Install:
Information on installing HDP 2.1 using local repositories (with HDP repo tarballs):
http://docs.hortonworks.com/HDPDocuments/HDP2/HDP-2.1.5/bk_reference/content/reference_chap4.html
Information on using Ambari to install HDP:
http://docs.hortonworks.com/HDPDocuments/Ambari-1.6.1.0/index.html