Strength Training-- Where do I start?

I've always been told that cardio is the key to losing weight. I'm now learning that strength training plays a much larger role than I ever realized. I've done some before-- I was a member at Curves several years ago for a short time when they were running a health trial and testing their "30 minutes, 3 times a week" tag line. That was my first introduction to any type of strength training. After this, I was a member of YMCA with my family where we were each given a fitness routine. Mine incorporated some weight machines, similar to those at Curves, but not to the same extent. When I was a member of Planet Fitness, before moving to South Carolina, they had a 30 minute circuit room, extremely similar to that at Curves. My best friend and I would always do a bit of cardio, but would finish our workouts in this room. I saw a ton of results when we were doing that routine on a regular basis. At that point in time, I hadn't made any changes in my diet at all. It was strictly exercise changes, so obviously, when we stopped all 50 of the pounds I had lost came right back. This time around, I'm doing things the right way, but now I don't really know where to start. I don't have the guidance I had at Curves or the Y. Some of the machines at my current gym are similar to ones I have seen and used in the past, but there aren't as many as I'm used to seeing. It has also been so long since I've used them, I'm just not sure what I'm doing. A lot of the machines are missing the information panel, so I'm not sure what muscles I'm working, or even which ones I should be trying to work for that matter. I tried some research on Pinterest, but haven't really found much that I think would work for me. I'm thinking of investing in a kettlebell of some sort, but I'd like to try the ones at the gym first that make sure that it's something I can stick with. If anyone has any resources that they think would be helpful, this is my call for help.