Thanks for the quick reply. Sigil looks like it should work. I may have to play around with it some. There doesn't seem to be any documentation, and I didn't see any option to import multiple txt files at once.
I found a round about way to do it for now. I have the full version of Adobe on my work computer. It has an option to combine text files. I used that and it imported all the files. I then saved it as html and used Calibre to convert to epub for Aldiko. It mostly works. There is no title page and the table of contents looks like html script or something form adobe. However, all the chapters are readable. Perhaps there is an easier or better way to do it. I just didn't know how to manually take 12 chapter files setup as text and combine them for a single book. Nothing seems to read that xml file for table of contents. I'll continue to play around. Thanks again.