Hi Kristian,
I wrote about this, here:
NethServer 7.2 alpha 3 - "First Blood"
and here:
NethServer 7.2 alpha 3 - "First Blood"
as a response to Davide.
From my experience, the first steps should be (short version):
1. Install the NS 7
2. Make the updates
3. Edit the Organisation contacts
4. Edit the Self-signed certificate
5. Choose the Account provider: Samba AD (Install from Software center), OpenLDAP (Install from Software center) or join to the existing one.
6. Proceed to add other packages you need