REI offers backpacking trips for any level of experience. I've heard of meetup groups, but you can get a wide variety of experiences. If you are looking for actual instruction, you are probably better off paying for it from a reputable organization.
People here can advise you on micro-steps, so that when you are actually in the wilderness you have the experience and confidence to have a good trip. There are many test backpacking trips you can take: sleeping in your backyard; taking your backpacking gear to a campground; day hiking with you backpacking gear then sleeping in a campground; an overnight backpacking trip within a mile of your car; and out-and-back overnight backpacking trip.... Take as many small steps as you think you need.
If you are concerned about gear, we love to talk shop! If you are retired, you are probably looking for lightweight backpacking. That is not the kind of advice you will get from REI.