the way to update is to download the complete package as it seems you have done.
then, unzip it and remove the blank config.php file.
then upload all the rest to overwrite the files on the server with the new ones.
if you did not remove the blank config.php file then you have overwritten your config.php file on the server with the blank one.
you will need to fix that before you can continue.
Knowledge Base - Rebuilding Your config.php File
once you have done that, go to :
then click on the update tab then click on update database only.
then wait until it is finished.
then delete that folder named install and you are done.