This post explains where you can buy a domain name.
You will find plenty of domain name providers and some of them will supply domain names together with hosting and you usually get a slightly lower price for it
However, that said, it is more preferable to keep your domain name provider separate from your hosting.
The online entrepreneur training provided by wealthy Affiliate suggests using a provider such as
As the title of the site suggests, you pick up domain names, very cheaply, or if you prefer, affordably
Top Tip here
When you search for the domain you want, you will offered other domains, as part of a bundle. Doing this reduces the cost of the package
Make sure you take advantage, because you will most likely need more than one domain name.