I am trying to modify a spreadsheet that I was sent. This spreadsheet
has a feature that allows you to hide and unhide columns and rows. You
use this option by clicking boxes labeled "1'' and "2" that are
located above the column numbers and in front of the row numbers. You
can also hide and conceal cells by clicking plus and/or minus signs
located in the same places. I want to expand this feature but do not
know how to use/create it. Any help would be appreciated.

Thanks!