The following is based on the assumption that you want the extracted data to land on your Marketing Cloud FTP.
Firstly, you'll need to ask Marketing Cloud Support to provision the data extract type you require (data extension), if you haven't already.
Then, after your SQL activity, drag in a data extract activity as your second step. You should now be able to select 'Data Extension Extract' from the drop-down for Extract Type on the Properties tab. For your file naming pattern, be sure to use something like filename-%%Year%%-%%Month%%-%%Day%%.csv so that you can differentiate between files once they start landing on the FTP.
On the Configuration tab, you'll meed to paste in the external key of the data extension you wish to export, so have this ready to copy, then configure the remaining details.
The third step in your automation will then be a File Transfer activity and you'll be moving the file from the Marketing Cloud safehouse to an accessible folder on the SFTP.
Once you've done the steps above, you should be able to retrieve the file.