1.) Creatine wont make you huge overnight, I don't know why you even took it when you are a novice to bodybuilding. If you get tired during workouts, it's because you are either a.) not eating properly (not enough carbs for energy), which is the case 90% of the time, or b.) not getting enough sleep (the case 10% time).
Your muscles grow based on what you eat. If you eat proper food (protein + carbs + healthy fats), you will grow as long as your routine doesn't overtrain you. If you just lift but eat like crap, you wont grow, no matter what your routine is.
If you are tired, it's because you have no food in you, to fuel your energy. Next time do this, eat lots of carbs and protein in the morning for breakfast, wait an hour and a half, then go work out. I guarantee you wont feel tired.
Eating is the key to it all. If you eat well, you will make gains even with a bad routine. If you have a good routine, but eat like garbage, you wont get anything out of it. Muscles need food to grow, and your body needs food in order to fuel your workouts. Once you can eat with dedication and never miss meals, never eat crap, you will start balooning.
2.) You can't lift 50 lbs. Who gives a sh!t. Are you a competitive olympic lifter? Do you have a competition tommorow? No. SO why the rush? Start with what you can lift, and keep adding weight every week little by little. If you can only curl a 40 lbs barbell, curl that, then next week try 45. Other then a few genetically gifted mutants, no bodybuilder ever goes into the gym on their first workout day ever and benches 200+. Don't rush it, everyone starts at the bottom and works upwards. Those people you see benching 500 and squatting 800+ were once like you.
If you can't make progress for some reason, 90% of the time, it's because you're not eating properly (not enough protein, not enough carbs) or 10% because you're on a bad routine and have overtrained.
3.) Other then protein powder, DO NOT bother with supplements until you've established a great eating routine. If you can't eat 4-5 meals a day of solid protein (chicken, steak, eggs, tuna & other fish, cottage cheese, milk) and healthy carbs (whole wheat bread, brown rice, baked potatoes, pasta, i.e. - no chocolate bars and sh!t), you have no business taking creatine, glutamine, m1t and god knows what else you impatient newcomers take these days.
4.) How do I stay motivated? By progress. I keep doing things properly, and I keep gaining mass. Why would I quit when I can keep getting bigger?