the day before yesterday I bought a domain via Dynadot. I also have the Advanced Hosting Plan and I set the name servers to advanced hosting. But when I look it up in the Web Hosting tab in my account nothing except my other website shows up. How can I make that work?
Your one Advanced Hosting package will support a minimum of 6 domains. To do that, you need to 1st change the Name Servers for your domain to Advanced Hosting (or ns100.dynadot.com and ns101.dynadot.com).
Once you do that, you log into CPanel and look for the "Add On Domains" icon and click on it. You'd fill out the information there.