With the help of Erika von Aspern, I think I have solved the problem of people not being able to post comments on my blog. The default settings only allow google account holders or blogger members to post comments, but I have changed the settings so that anyone can leave a comment.
Just click on "comment" at the bottom of any of my posts and a field appears into which you can type your comment. Then click "publish". If you want your name to be recorded as the author of the comment, add your name to the comment. Otherwise I will not know who sent it, because anonymous while appear as the author.