A

Right click the cell where you want to attach the comment.

B

From the drop-down menu click Insert Comment

C

Alternatively use Insert>Comment for the same effect.

D

Type your comment in the text box which appears.

E

Click anywhere to close the comment box.

F

Notice the small red triangle in the top right corner of the cell you chose - hover over the cell to read the comment.

G

Use Cell Right Click>Edit Comment to change the text in the box.

H

Use Cell Right Click>Delete Comment to delete it completely.