How do I make excel fit an exponential trendline to my dataset?

Hi I am trying to plot an exponential trendline following the data set on this graph. There are two sets of data (and, ignoring the sinusoidal appearance near the tail end, there should be two clear exponential curves. However when plotting an exponential trendline using the excel function the trendline does not fit the data at all.

The first image shows the graph without trendline.
The second shows the graph with a trendline plotted for the red data. As you can see the exponential curve should be curving upwards asymptotic to the x=0 and approximately y=110, but does not plot as such.

Btw I am using excel 2010.

Both the red and the blue. The curves should be reflections of one another. This data is referring to a physics investigation and the knowledge of theory states that the data should be exponential initially becoming more sinusoidal as the distance increases. For the sake of this i'd like to plot the line only for the first exponential. The blue line should be an exponential decay, with the red being a reflection.

No how do I do that?