Adding a comment

You can add comment either by the ExcelRange class or via the Comment Property of the ExcelWorksheet class. Comments can be added using plain text or using richtext as descibed in this example taken from Sample 20-.NET Framework or sample 6-.NET Core...

//Add Comments using the range class
var comment = ws.Cells["A3"].AddComment("Jan Källman:\r\n", "JK");
comment.Font.Bold = true;
var rt = comment.RichText.Add("This column contains the extensions.");
rt.Bold = false;
comment.AutoFit = true;

//Add a comment using the Comment collection
comment = ws.Comments.Add(ws.Cells["B3"],"This column contains the size of the files.", "JK");

//This sets the size and position. (The position is only when the comment is visible)
comment.From.Column = 7;
comment.From.Row = 3;
comment.To.Column = 16;
comment.To.Row = 8;
comment.BackgroundColor = Color.White;
comment.RichText.Add("\r\nTo format the numbers use the Numberformat-property like:\r\n");