the most important is that you have registered at Jobnet.dk but you also have to fill out a dokument/formular online at the website of your A-kasse. In danish it is called an "ledighedserklæring" = that you confirm that not have work any longer.
I assume of course that you are member of an A-kasse and has been for at least one year, otherwise you are not entitled to get uemployment benefits ("dagpenge").
You also must have worked for at least 1.924 hours during the last 3 years.
If you meet these conditions then also you must active apply for new job every week and also you must log ind to Jobnet.dk and write your joblog.
But you should already have been invited to meeting with your a-kasse or Jobcenter where they explain everything for you.