Adding comments to your worksheet allows you to share your thoughts with other users, or to serve as a reminder for yourself.
Right click the cell where you want to insert the comment, and begin typing in the box that appears. Click off the cell and you’ll see a little red triangle in the upper right hand corner of the cell where you just inserted a comment. This is a visual cue to let a user know that there is a comment in that cell.
To view that comment, simply hover over the cell, or right click the cell and select Show/Hide Comments. Hide the comment by right clicking the cell again and selecting Hide Comment.
To edit a comment, right click and select Edit Comment.
To delete a comment, right click and select Delete Comment.
Excel 2007 allows you to do all the previously mentioned actions on the Review tab under the Comments group.