If you have a document that needs to have comments and/or editing tracked, you can turn on that feature in Word 2010 and 2013 by clicking on the menu option Review. Look and click Track Changes, then track changes again to activate. To the left of the Track Changes option is Show Comments. Click that option to create the comment. You can place the comment by clicking at the end of a word or sentence and then type your comment where indicated.
For additional help and information about Track Changes, click the question mark in the upper right corner and enter track changes.