Thanks, Wayne, I really appreciate your reply, and this definitely gets me closer. I can put some borders on.
But not others. I'm able to put top, left and right borders on, but for some reason not the bottom border. Here's what I tried: 1) select the cell; 2) select border style of solid line; 3) select color of black; 4) select 3 pt; 5) click on desired border (last one). Nothing happens. I also tried clicking on the full box outline button (2nd one). It gives me the top, left and right borders but not the bottom!
Also, some cells seem to be completely immune to some borders (even following your directions), but not others. I can't figure out why.
I'm clearly closer, but I guess I'm still missing something? Is there some trick about adding bottom borders? (Have I jinxed things by starting with an Excel sheet that I imported into Numbers?)
--Paul