Assuming your goal is to reduce fat, get toned and increase strength and muscles, lets discuss what a beginners workout should be and how do you need to progress on a weekly or monthly basis.
As a beginner, you need to get adjusted to the strength workout regime and it would take a week or more to do so. First day at the gym focus entirely on the Cardio. Use various machines like the treadmill, elliptical trainer, stair climber, rowing machines and cycles. Its important to select a variety and pause for atleast 2 mins between these to get the benefits of interval training and to cut excess fat.
On day 2, start the strength workout targeting every part of the body from chest, back, shoulders and legs. Do not use heavy weights and just let the body get adjusted to the strength workout. Alternate the workout between cardio and strength for two or three weeks.
After your body gets adjusted to the strength workout. Split the workout into upper body, lower body and cardio targetting each for two days. example. day 1 upperbody, day 2 cardio, day 3 upperbody, day 4 lowerbody, day 5 upperbody and day 6 cardio.
Upper body workouts should target Chest, back & shoulders, biceps and triceps and Lower body should target Legs and Calves. Developing good lower body is an essential part of strength training.
Continue the workout in the split fashion above for a month. After that split the workout even further to target each muscle on a single day. Example: Chest on Monday, Back and Shoulder on Tuesdays, Cardio and Abs on Wed, Bicep and Tricep on Thrusday, Cardio and Abs on Friday and Legs and Calves on Saturday. ( Having a day off would be ideal).
Before each workout, do a 5 minute warm up and cool down doing stretching exercises after the workout. Also take regular protein and supplements to compensate for less food if required.