@Guilianna, new bike or not, it's arguably worth your time to learn how to fix a flat well before you're in that situation. As your LBS if they'd be willing to do a demo for you and then go home and practice. But at group rides, I'd say it's better off if you get a flat than if you're riding on your own. As people pass you'll, most will ask if you need any help and somebody would likely be able to help you. Still, it's a necessary skill to have regardless of the rides you do.