Before you start on a program of gym workouts you should always consult a personal trainer to ensure you are doing the right workouts for the results you want. Technique is also really important - it's very very easy to injure yourself in a gym.
A personal trainer can put together a series of gym workouts specifically designed for you and track your progress towards your individual fitness goals.
A personal trainer can supervise your gym workouts to ensure your technique is safe and they can also accurately monitor your progress as your fitness levels increase.
Never start on a new set of gym workouts without consulting a qualified fitness professional.