Contact me at firstname.lastname@example.org to receive the WP Estate child theme zip folder (minimum required to start the child theme).
Unzip the folder, and copy the wpestate-child folder to wp_content/themes/
Go to Admin – Appearance – Themes and activate the child theme from the list.
Any change you add regarding style.css, add it in child theme style.css file Advanced changes can also be added, but they may required some technical knowledge. This is the link to WordPress website about child themes http://codex.wordpress.org/Child_Themes