This tour starts at the corner of Pont des Arts and Quai François Mitterrand. This is on the Louvre side of the Seine river or where the Pont des Arts meets Quai François Mitterrand.
If you're not sure how to find this, the easiest is probably to go to the Louvre-Rivoli metro station on line 1 and exit the metro station (there is only one exit at this station). When you're at the top of the stairs of the metro station, don't cross any street yet. Look around for only building that takes up the whole block and is set back from the street. That's the Louvre. You want to walk with the Louvre to your right until you get to the Seine river, then take a right and walk along the river until you get to the first bridge. The Pont des Arts is the only pedestrian bridge in the area, you can't miss it. That's where I'll start talking to you!