To export a chart, you will need to have the chart created in a dashboard. From here, you will want to click the settings dropdown to the top right of the chart and click "Export" as shown below:
After you click "Export" our chart editor will display to the right as shown below (note: you can export a chart from the "Edit" section as well by hitting the export tab on the top banner of our chart editor; shown below):
We offer a few popular dimensions or feel free to create a custom dimension for your chart export, select your format, and click "Export". Your chart will immediately be downloaded.