Click “Option” under the “File” tab.

Click “Open & Export in the left menu and then "Import/Export".

Select “Export to a file,” click Next.

Within the Create a file type: select "Comma Separated Values" which is a CSV file, click Next.

Under “Select folder to export from,” select the contact folder that you want to export, and then click Next.

Choose a location and name for your backup file and then select Finish.

You can click here for importing instructions.