On the desktop site, you can add parents, partners, siblings, or children using the side pane on the left-hand side of the screen, or you can import an existing family with the import button at the bottom of the same pane.
On the mobile version, there is a pencil icon in the top right-hand corner of the screen which you can click to edit a person's details or add relatives. On that screen, the pencil icon will change to a tree, which you can click to return to the family tree.
