I didn't see your snapshot until I wrote this, but the concept is unchanged.
You need at least one series for the primary axis and one for the secondary. The secondary axis series can be the same data as on the primary, converted for the changed scale, or it can be a hidden dummy series. I'll do my example both ways.
Here is some simple data, with values in inches and centimeters. The first chart plots all data on the primary axis. In the second chart I've selected the centimeter data and plotted it on the secondary axis. They almost but don't quite line up, like your data. In the third chart, I've set the secondary Y axis maximum equal to 12.7 cm, which is 2.54 times 5 inches (the maximum of the primary axis). The data coincides perfectly. In the fourth I've hidden the legend and labeled the axes.
Below is simple data in inches with a dummy point for the centimeter axis. The first chart plots all data on the primary axis. The second plots the dummy centimeter point on the secondary axis. In the third chart I've made the axes coincide as above. In the fourth, I've added axis labels, and I've hidden the legend and the dummy point (formatting with no marker and no line).