For example: If you domain name is
http://www.info.com, you can create the page
http://www.steven.info.com for free using vodahost's capabilities (as long as you are the owner of info.com).
If you want to get a totally domain name, such at
http://www.material.com, you have to pay the $19.95 fee or however much it costs to get an additional domain name. You do not have to create another VodaHost account. You can run both websites on the account that you already are paying $7.95 a month for.
The only bad thing is you are only getting 5000mb space and 300gb bandwidth for each account. So if you had maybe 10 domains on one account, your space could become low (keyword "could").
5000mb and 300gb bandwidth should be plenty to run 3-4 websites, if not more. I wouldn't worry about the space issue.