I’m new at Mac and setting up my son’s old Mac to write booklets. I cannot find layout tab or theme tab.
First of all, there is no such thing as Word 4000.
Secondly, it's not at all clear what you're looking for when you reference 'layout tab' or 'theme tab'. Any modern Mac is able to use a variety of word processing software, but that may not be what you need for your goal.
You need to be more specific as to what you're trying to accomplish, and what software you're currently running on this Mac, as well as which version of Mac OS X it is.