How to get the correct URL on my wordpress site?

A combination of answers for you. To remove the “wordpress” from your URL path, I would recommend the following step-by-step on “Using a pre-existing subdirectory”.
http://codex.wordpress.org/Giving_WordPress_Its_Own_Directory#Using_a_pre-existing_subdirectory_install

The end result will be your WordPress content pages at “mydomain.no” instead of “mydomain.no/wordpress”.

The second part of the problem will involve writing 301 redirects for the URLs that will change. PDFs and other files hosted in the media library will have new URLs. That is not the disaster that you may think. Creating a 301 for every URL that changes preserves Google rankings and existing links to the content.

The format for your redirects should look like this:
redirect 301 /oldfile.html http://mydomain.no/newpath/

Paste this into the .htaccess file, directly below the WordPress rules you find there.