What gear is essential for your first hike?

I've been wanting to join the club's weekend hikes but have no experience. Could anyone share advice? For a beginner-level trail, what gear is essential?

I currently have a pair of sneakers and a regular backpack. Is that enough? Also, how long before departure should we gather? Do I need to bring my own water and snacks for the midway rest stops?

If you know someone who'd like to join, feel free to coordinate in the comments—we can look out for each other on the trip.