If he has no profile manager and his profile is open (white lock) or public (green lock) then you can "adopt" him (WikiTree's word for becoming his profile manager). You should see a link next to where it says "No profile manager" that you can click to "adopt this profile".
If his profile is private (red, yellow or orange lock) then you need to write to email@example.com and tell them this is your father's profile and you want to adopt it - they'll take care of it for you.
When you are the manager, you will be able to connect him as your father. You will also be able to change the privacy level if you wish.