It was easy not as hard as I thought.
I assume you have one site on your synology NAS that you created with the wordpress package (the synology package).
Make a folder to the site in web ( web/yoursite )directory and point the virtual host entry to that folder.
Then download the latest wordpress from this site.
Unzip the wordpress folder that you downloaded from here into the web/yoursite.
Then Create in php admin the database. This process is well documented on this site.
Then it will work.
Of course you need to get your url to point to the synology too.