Hello yodakim,
In order for you to start receiving free diamond, you need to confirm the e-mail address, used for registration of your account. To do this, go to menu Settings in the lower left corner of the screen, Personal settings and Account info tab and click on "Send a confirmation e-mail". On the same e-mail address, you will receive a message from Imperia Online, including a link, by which you will complete the confirmation. After that you need to answer a question from Polls in the game. You will find Polls in the upper left corner of the screen ->
http://prntscr.com/5x6x1f. If your registration email is confirmed and 3 days from the registration of your account have passed, you'll start receiving a free daily diamond for each answer.