Well I got it working!
And I can describe the steps to add a admin in a couple of lines, don't understand that it is so difficult to explain to someone like me with no nerdy background.
I will make a tutorial about making a login system with administrator in the near future. That everybody will understand!
Thanks a lot for your help!:)
The only problem I encounter is that the Access Page Manager only works when a page that needs treatment is not opened in Dream Weaver. When you close it and take an other page it works.
Get a warning: "CAN NOT MAKE THE CHANGES ON THE CURRENTLY OPENED PAGE IN DREAM WEAVER"