inputBox if cell >" ?

In my worbook have a column of 20 cells. Any one of the cells, up to all 20, can have text in them. If there is text in those cells, I want/need an inputBox to appear so that a comment can be typed in. The result of the input box will go to a cell out of sight on the same page of the workbook in a relative location to the 20 cells.

I've thought about having commandbutton next to each cell so that the user could select which one she/he wants. That much vba I know and can do. The other thought is to press a single button and programmitically search out the text filled cells and prompt the user for a comment (I like this idea a bit better), but only if the comment can be placed relative to cell that prompted the action.