Welcome Olli to the ESOUI Community.
Copy (CTRL + C) the following line:
%userprofile%\documents\elder scrolls online\live\addons
(This line works for all windows versions and languages)
Open your Windows Explorer (Windows Button + E) and paste (CTRL + V) the line in the navigation bar.
Press Enter and you are in the right directory to install addons.
You can also use this line as directory input for unpack addons.