As far as I remember the 'standard' C# toolbox doesn't have a chart control, so the one you are adding to your app must be an addition. Therefore we still do not know what chart you are using.
Bearing this in mind the only thing that I can suggest is the following.
When you add the chart to your form a line will be added to the
MyForm.designer.cs
file that will look something like
SomeTypeOfChartClass whateverYouNamedYourChart;
If you copy the bold underlined bit (from your file, not from here) and paste it into the search box on Google/Bing, I'm sure that you will find lots of useful information.
From what you have asked so far, it would seem that you might be a little out of your depth, waiting to be spoonfed by the members here will not help you as much as doing your own research will.
Good luck! :)