Guide for fresh magento 2.2 new theme and child themes' installation in new domain. Need to activate the Greek Language pack and the child themes with sample contents like demo site.

Guide for fresh magento 2.2 new theme and child themes' installation in new domain. Need to activate the Greek Language pack and the child themes with sample contents like demo site. The server is already full set up because already runs several magento2 sites Need full written instructions how to do the same in another domain in the same server. How to make fresh installation and how to add a new theme.