There’s no direct search function in the app, so you can’t look up a specific user by name. However, if the person you are looking for is in a group or community, you can browse the member list by tapping on the group header to open the group information screen. Then, tap "See All" under the Members section, where you can use the search bar to find someone within that group.
I accidentally swiped left when I meant to swipe right. How do I find that user again?
If you swiped left by mistake, you can use the Rewind feature to go back and find that user again. Just tap the rewind button in Zapping that is on the bottom left corner to undo your last swipe. Keep in mind that this feature is only available for Plus or higher members.