how do i authorise my ereader with Adobe?

I just cant find where the "Manage Library" bit is, is it in Adobe or in my KOBO - I want to throw it out of the window!!

1. Connect your Kobo eReader to your computer and select Manage Library.
2. Start Digital Editions.
   If you were already using Digital Editions, restart it so that it will find your eReader and start the Device Setup Assistant.
3. Click Authorize Device.
4. Click Finished to complete the process