A Domain Name is a word that we choose in order to access a webpage easily, without having to remember the IP address of a site.
The word is always followed by a TLD, which is a dot (.) and a short code which usually refers to a country.
So, a Domain Name with TLD .gr should be like something.gr and we can access it by typing https://www.something.gr on a browser window.
At the top of this page you can choose and register a Domain Name.