2. You have to add support.webshooter.se to your dns server settings, these are the dns servers for webshooter.se.
webshooter.se. 23326 IN NS ns1.namesystem.se.
webshooter.se. 23326 IN NS ns2.namesystem.se.
webshooter.se. 23326 IN NS ns3.namesystem.se.
I suspect that you host your domain on the dns server of the hosting provider where you bought it, usually you have a webinterface were you can add/remove/modify dns records. Looking at the information of the ip adress of the first dns server it hosted by the provider "GleSYS".
So I would expect that you have some sort of login account that you can login an account there to manage your dns records. That will also be where webshooter.se is defined, so this record.
webshooter.se. 3600 IN A 188.8.131.52
Glad that it's just for personal learning and voluntary working, that's a great wait to gain experience!