It seems that you didnt login in your WHM so far. You need to login in your WHM from the URL specified in the welcome email. You will need to spend 5 - 10 mins in watching cpanel and WHM tutorials located at
http://www.eukhost.com/support/
People who get addicted to WHM hate other control panels. I hope you will do the same in next 2 - 3 days. See the number of features and see the level of development that has been done on WHM.
Let me know when you start adding your other domains from WHM. We give only 1 GB space for the cpanel account that is created for your main domain and remaining 6GB space is there for your WHM to assign to other domains. Make sure that you add packages from your WHM before you start adding domains from "Create new Account".