To Comment you can be a Registered User, Anonymous, a Member/Follower of the Blog or a User with a Google Account ..
You can see at the bottom of the blog post, 0 comments etc ... if you click on that, it will take you to the form where you post your own comment.
It is so easy that I have forgotten how to do it but this is generally what you do.
I hope this makes sense and is helpful. I love hearing your kind, helpful, funny comments .. I don't want advice but everything is else good ...
Thank you !