In the Contacts section, you can see all the contacts in your account. 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.
You can choose columns that you want to export. Choose the columns you want to include from the right hand side of the page.
After you select the columns you want to include, those will be visible on the contacts page. After that, you need to go to more and click export.
You'll see you have two different options here. You can either export with the displayed columns, or you can export with all columns.
After you export your contacts, the export file will be automatically sent to your email. Congrats!