How do you make a barycenter point?
1 - Click on the "Box Select" tool.
2 - Drag a box around the 2 bodies.
3 - Click the "Add Barycenter" button in the selected bodies panel.
OR
1 - Select one body.
2 - Hold down the Ctrl key on your keyboard.
3 - Click on the other body.
4 - Release the Ctrl key.
5 - Click the "Add Barycenter" button in the selected bodies panel.