Training correctly is so important! Training comes down to everything; you can't just go in lift and get big. Some can, those are the people we are all jealous of because they are genetically gifted. However for us ‘normal’ people our training should involve a good choice of exercise's with a good weight.
‘Good’ weight varies from person to person; don't try lifting more than you can handle. You will either do some serious damage, or look like an idiot stuck under it. Everyone started somewhere, even the likes of Cutler, Warren or Heath (IFBB pro-bodybuilders) didn't start on a 100kg bench press. Technique is also important, you want to lift the weight not throw it. You have numerous things that are important to know. Your body although needing to train and constantly improve to grow, actually grows outside the gym. This is why sleep is essential as part of your program, 8 hours is a good time to aim for. You then have things called sets and reps. Reps are how many time's you do an exercise for in a row. For example if you do 10 push ups in a row, you have done 10 reps. If you pause and do another 10, you have then done 2 sets. So you have done 2 sets of 10 reps.
Before you train warming up and stretching should be done to prepare your body to help avoid injury. Shoulder joints are known to be a common problem for people, which is why warming up should always be done before any workout! Stretching should be used in between sets and after your workout. To warm-up you would go for a lighter weight and work upwards in weight, concentrate on not throwing the weight. To start with, a good program is to divide your body in half, upper body and lower body. Aim to do two exercises for a muscle, e.g. two for chest, two for biceps etc. I would start with aiming at 3 sets for each exercise. Your rep range would depend upon your goal. Upper body one day then either lowers body the next, or a day off then lower body. As a general rule to gain you want a lower rep range of around 6-10, and to lose body fat in the region of 10-20. However, everyone has different views on this. You need rest in between workouts though to avoid over training or injury. Most people will do two day's exercise then one day break. Again research all the option's but remember if you are starting out then training like Jay Cutler is not wise! Overtraining is when you simply do too much; which will potentially result in muscle loss, injury and boredom. The best thing to do is start off slow, take it easy and enjoy it. If you keep a log, weigh yourself and take photos every month it should help you see your progress.
Overall as a beginner, get your diet in check and set yourself a training program and once you have done this get the basic supplements in as well! A good place to start for friendly, unbiased, un-judgmental advice is the FitForum and FitMag! There are a whole host of people from expert's to beginners, check it out it and you may be surprised what you can learn.