What is a Domain?
A domain name is purely a name you register with a domain registrar such as Rebel.ca and on it's own has little value. Most people choose their business name as their domain name.
Just like I have colourinfusion.ca. You need to attach hosting in order for you to be able to upload files for the world to see.
How do I choose a domain name?
Usually people pick their business name as the domain name. You can check on rebel.ca to see if yours is available. If not, you can add a keyword to it.
Can you recommend a Domain Name Registrar?
I would recommend rebel.ca as they have great customer service and live chat on their site.