Okay, this is what I've learned. You CAN put your include command in your template, but you have to go into your code and take out the "../" before the name of your include file so that the text the template kicks out will look for the include .txt file on the same level as the parent document. (Your include .txt file must be on the level as the parents document.)
Creating my include .txt file worked for me when I created a table first, then used the navigation setup on the object bar. I then selected this navigation table, cut it from the parent doc, then created a new file, went into code view, deleted all the intial coding, went back to design view and pasted in my table. Went back into code view, cleaned it up so it was easier for me to read and understand. Check the parent doc, it may still have all the javascript at the top which can be deleted.
I think I've accomplished what I set out to do -- remove all the coding that could throw off the weight of my keywords the search engines will calculate. I've also got shared content that's in an include file that only needs to be edited once to change all pages -- although it's a bit cumbersome to edit. The only way to get my include .txt file into design view to edit it, that I can see, is to create a test.htm page, go into code view, add lots of space after the <body> command and paste in my include .txt file. Then I can edit in design view. But before I save I have to remember to go in and take out all the top and bottom code from the "new" doc and save it as my include .txt file.
Hope I've explained this well enough to make any sense. Oh, I did have to make my doc's .shtml to work on my server, though that may not be necessary with another server.