Yes, you would have to purchase your domain seperately from the hosting package. No plans at Surpass give you a domain.
Add-on and parked domains are additional domains that you can add to your account. More information about them can be found here;
What Would You Do If...
The reason Surpass doens't give you domains with your account is that a) it raises the price of the hosting, b) many people already have a domain and c) it allows the hostees to have full control of their domain if they choose to leave.
You can also save a lot of money registering your domain at GoDaddy.com rather than at Surpass Domains.