One crude but fairly simple way is just to use Excel (or another spreadsheet), enlarge the cells and put borders on them to make your rectangles. Fill in the boxes with the names of the stalls, etc.
Getting things to accurate scale can try one's patience, but you should be able to twiddle with things to get close enough - if I understand your description of what you need, and if your layout isnt' too complex.
You can also do the same in Word by creating a table, borders, etc.
If you have a reasonably good illustration program like Illustrator or Photoshop, or even Paint, it's of course pretty easy to draw lines, circles, etc, although not so easy to draw to an exact scale with many of them. If your rectangles aren't in nice "squared up" rows, this might be easier than using tables in Excel or Word, even if you have to settle for "optical accuracy"1.
You can probably find a "drawing" program, either freeware or fairly cheap, but even the simple ones may require some learning to figure out how to get what you want. There are quite a few pretty cheap ones for landscape layouts, office and furniture placements, or even "organization charts" that could be pressed to do the job if it's not too complex.
1 Optical Accuracy = scoot things around until it looks right - also called eyeballing it.
Another old-fashioned way is to cut out little rectangles (perhaps after you've printed the text/content on them) paste or transparent tape them to a bigger page, and take it to your nearest print shop and make a copy.