1. Walk to Charles de Gaulle - Étoile metro station (5 minutes).
2. Take metro Line 6 towards Nation, and get off at Bir-Hakeim station (1 stop).
3. From the Bir-Hakeim metro station, walk for about 5 minutes toward the River Seine, and you will see the Eiffel Tower in front of you.
The total journey time is approximately 15 minutes. You can also purchase tickets for the bus on board.