Yes you are right. Admin need to explain this because this is what I want to choose. Because If I will choose Addon Domains and transfer all my web site files there then maybe whole wordpress admin maybe will not working. I’ not sure. I hope Admin will see this problem and answer me to find a solution asap.
By the way thank you all for your help! 
The message above was scheduled to post it yesterday but there is a limit for messages.
So now this is a new post:
Hello Admin,
I would like to park the domain name I have in other registrar and the domain is www.mygardenplants.eu
So how I will connect this domain to my account? Is there any way to do it now? Because many days before I was achieved this succefuly but I can’t do it now.
As I can see now from cPanel you have disabled the Park Domain feature. Why is this happening; There is no field to assign my domain.