Open your Google Docs document
Select the text or place the cursor where you want to comment
Click the comment icon in the toolbar
Or use the keyboard shortcut Ctrl+Alt+M on Windows or Cmd+Option+M on Mac
Type your comment in the comment box
Click Comment to post it
To mention someone, type @ followed by their name or email
To reply to a comment, click Reply under the comment
To edit or delete your own comment, click the three dots on the comment
To resolve a comment, click Resolve on the comment thread