You can find your email statistics for your system in general by going to the left-hand side of your account and clicking My Marketing Tools > Email Stats. Here, you can see an overview of your autoresponder stats, in addition to your email broadcast stats as well.
You can drill down into your email stats by going to Email, Text, Voice > Emails Clicked or Emails Opened or Emails Sent. Here, you can find and see individual emails that have gone out to individual contacts.
You can always drill down into a particular contact's email stats by going to Contacts & Leads > Contacts and clicking on the blue box with a contact's name to view the emails that have been sent out to them.