If you have never lifted, then do not lift heavy at all. There are 2 aspects of lifting: 1. the technique and 2. the amount of weight you lift.
I have had both a power lifting and Olympic lifting coach (weightlifting) and, in the beginning, I practiced doing the lifts properly without regard to how much weight I could lift. Once I could lift with proper form, then I was allowed work on getting strong. I worked on form this very day at the gym.

You'll get a great workout just learning to do these moves. Don't start the program yet! Learn to correctly and safely squat, overhead press, bench with a light bar, row, etc.

I lift 3 times a week with a trainer and I still get frightened going into new territory, lol! It's not a bad idea to be cautious like you are! It helps to avoid injury if you take your time to find out how to pick up weights.