Facebook is a social networking tool that has attracted a massive following, in part because it allows users to conveniently keep in contact with one another. One of the features that helps people interact is the ability to post and comment on photos that have been uploaded to the service.

Sign into your Facebook profile.

Enter the "Applications" area and click on the "Photos" tab. A new page will load that displays all of your friends' photo albums. Click on one of them to load a new page displaying thumbnails of each image in the album.

Click on the thumbnail of the image you want to comment on. A new page loads displaying the photo at a higher resolution.

Scroll to the bottom of the page to find a text box that reads "Add a comment." Type your comment into the box and click the "Add Comment" button.

Refresh the page by clicking on the "Refresh" button of your Internet browser. You should see the comment displayed underneath the photo.