very basic question

This is definitely a blogging 101 question.

So if my hosted and registered domain is annieflorinphotography.com, how do I create my blog so that it’s annieflorinphotography.com/blog? Do I have to register and host that new domain or do I create it as a subdomain or an add-on to my current domain? If so, how?

I’m hosting through Bludomain.

Thanks so much for any help that can be offered!