On the docks, near Alma bridge
Place de la Concorde (Pass By)
Louvre Museum (Pass By)
You can cancel up to 24 hours in advance of the experience for a full refund.
I recommend going later in the evening as you are able to see the lights of Paris and experience the Eiffel Tower at night.
Search for the Bateaux Mouche port and you will be fine.
If you have the time do it but you might be better off with other excursions.