I’m scared to go

My lgs is having its first ever op event and in tune with the release of the st15-20 decks. There will be games held aswell using the new st decks. I’m very worried to go cause I don’t fully understand the rules and game turns yet. I am worried someone will get annoyed while I try figure out what card I should play etc. I’m probably going to be a slow paced player. Any tips ? All welcome 🙏