Garden planting time is already over so you can't plant much this year since it's July. You can plant some quick growers that are cold tolerant potentially but you missed most of this year. Which isn't a problem because there's tons of prep that you can do next year.

I would recommend reading some books about permaculture or organic gardening to get some basics but you are going to be basically growing your soil this year which is the key to sustainable good gardening. If you a spot in mind you can start Sheet Mulching right now. You can mow down whatever is there and cover with cardboard boxes (great use for those moving boxes) and then start covering with more material throughout the year. This a great way to start. You can also start Solarizing a place if you want to seed. If your in North America fall seeding works amazing for natives and it takes a few hot months to kill all the weeds seeds from a site so it's perfect to get started on it.

As far as engaging community start by contacting master gardener programs which usually have regular meetings. You can also give your extra vegetables (next year) to your neighbors which is a great way to build connections.