Edge scrolling manual tutorial

Having difficulty following the Construct manual Edge Scrolling Tutorial. What or where is 'scroll X', and what or where is 'scrollX'? How do I access them or create them? How do I place 'System Set scroll X to scrollX+scrollrate' as an action? I cant find any such events or actions. I'm using Construct 2 release 216 personal license.

System action, System expression, System conditions.

When you have the dialog to add an action (or create an event), the first object type available is named "System" and that's where you find system actions, conditions and expressions.

Amongst which "Scroll to X".

"ScrollX" is a system expression.