The following animated tutorial shows the process of adding the first person to a new file and using Diagram Drag to add people to a tree.
This tutorial is for Family Historian Version 3 on Windows XP, but despite slightly different layout and colours, many concepts are still valid for later versions.
It is also possible to add a person using Add > Unrelated Individual which uses the The Property Box is the primary window for data entry and for viewing details of stored records. It is used with records of all types. , to which new Parents, Spouses, and Children may be added via blue links.