You will need to first find the campaign that you would like to export the chart from.
Click "Campaigns" on the left hand navigation bar, and find the desired campaign.
From the dashboard of the campaign click "View Full Statistics" this will take you to an overview of your campaign statistics.
Select the criteria you wish to display for the chart, then click the three little dot button on the right hand side of the chart, from there you can export the chart as a JPEG or PNG image file.
