It is in mine under the 'My stamps' category, would depend on exactly which stamps you have but mine is on the second-to-last page with the rest of the stamps from that event. It looks like 'My stamps' is categorized by Easter > Halloween > April Fools > Summer event, and then the years count down from most newest to oldest, and the Space Event was 2016 so it should be between the Candy event and Lost City/Underwater event stamps.