You could find your position in the event ranking, as well as the rewards offered, by tapping on the red event widget. There you will find all the information related to your event progress.

But, take in mind that you MUST enter the event before it ends to claim the smaller progress rewards (gems and chests) offered each time you complete a specific tier. Once the event has finished, those rewards could NOT be claimed. You will only receive the RANK reward after the event.