OK my take on this is to ask for a trainer to get you set up. Usually there is someone there to make sure you are doing things properly and that person can make suggestions for your workout.
A lot depends on what you want to accomplish. Are you going for a lot of weight lifting or general fitness? I do some cardio each time that I get to the gym, then depending on the schedule I work on the machines or swim, or do some more bike or walking.
Start out light. If you are sore you may be hitting it too hard at first.
Pain does not mean gain.
I started with a program set up by a trainer, who followed up with me every couple of weeks and changed what I did according to how I was progressing.
A good source of information is "My Fitness Pal" on the internet. It gives a lot of tips on getting the most out of exercise and also diet suggestions. Also a good site is " Map my Walk." These are Under Armor sites and you can score some good deals on workout clothes and equipment.
My workouts may not be as Macho as some on here suggest, but I am getting in better and better shape, don't get too sore from overdoing, and enjoy the workouts.
The best hint I can give you is to get in the habit of doing your workouts regularly. It is easy to say, I don't feel like doing that to day, and then the next day letting it slide.
Don't wait until you are over 60 to try to get back in shape like I did.
Good luck.