In the Contacts section, you can see all your contacts at your account. To be able to export them, all you need to do is to filter the ones you want to export. You can check how to do advanced filtering to your contacts, or you can simply export them all.
After clicking on the contacts section, you need to go to more and click export.
You can even choose columns that you want and after that export them easily.
Please mention that they can choose columns to export and show how they can choose columns in a screenshot.