To get start, right click on "Computer" on the start menu and select "Properties".
Click on Advanced system settings.
Now click on the Computer Name tab and click on the Change button at the bottom:
Now click on the Domain radio button and type in the name of the domain name (Dardanelle.local) that you want to join this computer to.
It will prompt you for a username and password. Any account should be able to join to the domain, it does NOT have to be an Admin account.
You may have to type your username in with the Dardanelle\ in front of it. Ex: Dardanelle\jon.george