Looking for procedure to install HDP 2.6.1 on CentOS 7.3 (or the closest supported version to CentOS 7.3)

[#1]

Closest supported version is CentOS7.2 and you should refer below documentation for the same.

https://docs.hortonworks.com/HDPDocuments/Ambari-2.5.2.0/bk_ambari-installation/content/ch_Getting_R...

[#2]

The 7.2 instructions should work fine on 7.3.

[#3]

@Rajesh Chopra

Are you looking for a step by step help?

If so can you provide info about the number of nodes you plan for your cluster and memory on each host?