If you win a prize then you'll automatically be notified via email and the my account > messages section of your Slots Temple account.
If you think that you have won a prize but not received it, the likelihood is that the tournament hasn't finished yet. To double check this, simply visit the Tournament schedule and click on the 'i' information icon of the tournament in question. The 'Ends in' information will then be visible (example image below showing a tournament that still has 2 days before it ends).