How can I use the gym to get, and stay in shape?

I have access to a complete up-to-date modern gym with everything imaginable in it except a fitness instructor. I am a 48 yr old male, 5'10" - 195lbs. with a slightly showing gut. What I want to do is go into the gym using some instructions, and/or pictures and go from machine to machine per a scheduled routine. Can someone advise, and/or send me to a website, and/or recommend a good book.