Hi Debbie,
I know this will be hard to believe, but don't worry about that too much right now, as you are going to have lots and lots of practice by the end of the course. Don't confuse yourself with other books, because the books that have been provided with the program are the best ones. I know if you contact Instructor Debby, she would be more than happy to try to explain things. But, really, I think we all have had trouble with the 5th digits and E codes and V codes, but it really will click. :)
Best of luck to you!
Paulette