error by upload photo/template

Hello,

I have wordpress installed. But if I want to upload a photo or a template I receive error: Unable to create directory wp-content/uploads/2017/03. Is its parent directory writable by the server?

I have searched the internet for a solution and got the following: There is in that you are in the file wp-config.php the line:
define(‘UPLOADS’, ‘wp-content/myimages’);
can add.

The above line should be for the line below.
wp-config.php:
/** Sets up WordPress vars and included files. */
require_once(ABSPATH . ‘wp-settings.php’);

I did this but when uploading I get the same message. So I can not upload anything.

My question is: How can I solve the error “Unable to create directory wp-content/uploads/2017/03. Is its parent directory writable by the server?” so that I can upload images and templates?

thanks in advance