Where do I buy a domain name (also called a web address)? The short answer is you should be able to buy it from your hosting company, but you can literally buy it anywhere and just redirect it to wherever you bought your website’s hosting.
They will cost different prices at different domain “registrars” (companies you can buy a domain name through are called registrars), but buyer beware, because really all those companies are just acting as salesmen for the same business – in this case ICANN.
And they will charge differently – so you may get a deal one year for $1 for a .com domain name, but next year it’ll be $30 (or usually $14). So don’t just look for this year, see what the renewal price will be too.