The lessons precede from 1 to 13 and the keys are presented in a logical order to be learned. The home keys are dthe and they are in lesson 1a and 1b. I have assigned filenames to the lessons that start with the group number for the new keys that have just been introduced. The key group is followed by a letter starting with a. Group 1 has lesson 1a and 1b. The first few groups have only a couple lessons as there are few keys.
Later groups have more lessons.
I hope you will make even more lessons. No file extension has been given to make asking for a lesson as short and sweet as possible. DOS does not require an extension. You may assign any legal filename to your lessons. Remember that you will have to type in the filename when you want to do the lesson.