I notice there is a Reminder List.  I would love to be able to make a list of books that will come out in the future, or series that I want to remember but I don't understand how I add books to the Reminder List.  Could someone help?

When you find a book you think you want on your reminder list, there will be several options to the right of the book.  One of those you can click to add it to your reminder list.   IF you find a book somewhere OTHER THAN PBS, you can put the ISBN or title of the book in the search and then add it to your reminder list.

IF you go to the Help Center above and put in Reminder List you will find these helps:

Once you find a PBS listing for a book you want, and you are viewing the book details page (page where it shows image of the book, and the description etc.) on the right side will be a list of things you can do pertaining to the book. 

Clicking on the +Reminder button will add the book to your Reminder list. 

I guess my problem lies in that the book I want hasn't an ISBN yet.  It's the next book in a series I'm reading and not due out for a few months.  I just don't want to forget about it and get it on my wish list asap.  I gues I have to make a list elsewhere.

Most books are assigned an ISBN long before they actually hit the bookstore shelves - sometimes as much as 6-10 months ahead.  I usually find those ISBN's on Amazon or the author's website.

The wishlists for popular books start to build as soon as the ISBN is assigned.  I advise you NOT to wait until the book is released.    Find out that ISBN as soon as you can and get in the PBS wishlist line. 

Here's an example on my wishlist - Indulgence in Death by J.D. Robb.   It doesn't come out until November - 5 months from now.   I found the ISBN and added myself to the wishlist for this book in April - 7 months before release.  But even that was late because by that time I was #108 on the wishlist.  NOW the wishlist is up to 162 wishers.    There will probably be several hundred more wishers for this book before it is actually released.

Of course, this is an example of an extremely popular author - and a hardcover book.  Not all books with have such long wishlists.  Still .... DON'T WAIT.

And to add to that info, if you find the ISBN elsewhere and do an advanced search for the ISBN (other searches may work too) that triggers the server to go out and look for info on that ISBN next time it updates the database.  Search again the next day, and it may be there.