You need to choose a line that has a continuous group of samples and somehow count how many samples occur in a given time period. Do the math and that will be your time resolution. I am not sure if you will really be able to tell given the nature of the graph, unless you can somehow zoom in on the data to count it reliably. If you really are sampling at 10 MS/s and you want to know the time resolution based on that sample rate, it will be 100 ns.
I am still a bit unsure of the data since you have multiple samples on the y-axis that correspond with a given x-axis value. When you measure anything, you can only have one voltage value correspond to one time value. For example, a signal cannot be both 0.001 V and 0.006 V (or any of the many other values in the graph) at the same exact moment in time.
Regards,
Daniel S.
National Instruments
