Depending on your current settings for your comments, you may need to approve them before they are visible on your site.  You will see a notification with the number of pending comments in both your side and admin bar.  Click on either of these to take you to the comments page.  Here, you will be able to see all of your comments, whether they are pending or approved. You can filter them by clicking on the options here.

To approve a comment, simply hover over it and click “Approve.”  You can always un-approve a comment that you have already approved if you wish.

You can also reply to to a comment from this page.  Just hit “Reply” on the comment, type in your response and hit “Reply”

You can designate a comment as spam or send it to the trash, which will put the item in the corresponding filter.

Clicking edit allows you to change any aspect about the comment; like the authors information, the comment itself and its current status.  Click update if you make any edits.  Or you can move the comment to the trash.

When a comment is in the trash you can still restore it.  Deleting it permanently completely gets rid of the post from your site.