Need Help With an Array

Can someone suggest a simple routine routine to do the following with an array.

The array is 10x12. Each cell in the array has a letter in it.
What I would like to do is type in a letter, F for example. Then every cell which contained F will highlight. I would repeat with more letters and they would highlight also. Each letter would be highlighted with a different color.

I don't know visual basic so I am hoping I can do this with regular excel formulas.

I don't need prompts or any dialog. I am good with just typing info into a cell.

I know simple stuff on excel and have used a few formulas but this particular thing I don't know how to do.

I really didn't think much about exactly where to type in a variable.
I didn't mention what this is for but for clarification, it might help

What the array represents is the neck of a 10 string steel guitar. There are 12 frets, so the array is 10x12. The letter typed in is a note. The highlights would show every place on the neck where that note can be played. Sometimes more than one note would be typed in and they would all need to be highlighted at the same time but each with a different color. I appreciate the help. I need to sign off for the night.

What you already sent works just fine. There needs to be 1 more column for open strings.
Then there needs to be a way to enter notes with sharps and flats.
I replied yesterday but for some reason that doesn't show up on the thread.