Host an event: a meetup, edit-a-thon, workshop, or casual get-together. 29 events are already in the works. Yours could join them! Add it to the calendar: https://www.wikidata.org/wiki/Wikidata:Fourteenth_Birthday/Calendar
Besides hosting, you can also share a birthday present for Wikidata and its community on the Presents & messages call, where everyone comes together to share birthday joy: https://www.wikidata.org/wiki/Event:Wikidata_Fourteenth_Birthday/Presents_%26_messages_call