You can set the number of POSTS PER PAGE in the Control Panel under the main tab "App Settings" and then select "General" from the sub menu.

Thanks so much. That was the answer. Setting the number of posts per page to a lower figure (3) allows me to continue have somewhat long posts, but have page breaks (and Next Page links) at appropriate places on the page.

I had looked at that App Settings/General panel previously, but completely missed that setting because of the confusing way the entry location is labeled: "Posts/Days per page:"

Thanks for your instruction. All is well now.

Let me add something to my own post, because the more I have learned about B2, I have found some useful information, which I should have studied before I asked my original question.

There are already provisions built into the software which will solve the original problem I stated, without having to change the number of posts per page. What I was really looking for was a way to force a page break in a very, very long post which would just keep "going and going."

Here is what was provided in one of the example posts that came with the install (they kept telling me to read those, but it took me a while to realize that was good advice):

This is page 1 of a multipage post.

You can see the other pages by clicking on the links below the text.

<!--nextpage-->

This is page 2.

<!--nextpage-->

This is page 3.

<!--nextpage-->

This is page 4.

It is the last page.

That <!--nextpage--> mechanism is exactly what I needed.

Plus, they also described another method using this entry:

This is an extended post. This means you only see this first part by default and you must click on the link below to see more.

<!--more-->

And if you don't want the first part to show after they click use this:

<!--more--><!--noteaser-->

So, there are some very nice built-in mechanisms to achieve what I needed (forcing a page break). I am now using the excellent <!--nextpage--> approach. I didn't need to change the number of posts per page at all (I think that five or even more is appropriate), but I am not burdened with pages that are too lengthy, because of a long article.