a b d c a
a f g e a
c g b f c

I will have a table with many letters in it like the one above but with more letters in it.

I need a way to type in a letter. If the letter matches one or more cells, I need to highlight each cell that contains the letter.

If the letter I type in is a, all of the cells that contain the letter a would turn a certain color, like red or blue.
In some of the cells, there might be one or more letters separated by a comma. The sell would light up if the letter a for example was anywhere in the cell. For example,
If a cell contained just a, it would highlight. If it contained (a,b,c) it would highlight.

What the table represents is the neck of a pedal steel guitar. The excel formula is to find every fret where a certain note occurs. I included that to give an idea of what I am trying to accomplish.

Thanks

Jimmy