you should consider 3 factors, eating, training and sleeping.

eating can be said as the most important, but it is useless without the other 2 factors. similarly, it goes the same for the other 2 factors. they compliment each other.

post up your diet. n use a calorie counter ie fitday.com, register for free n use online. supplement is to enhance the progress once your lifestyle n diet is steady. for now, u can start by eating less carbs for every meal.. except post workout.. thats the only meal u want to eat carbs if possible. eat more protein instead. n healthy fats.

train at least 3 times a week with at least 48 hrs rest in between, more if you need. are your 6 reps done with weights that allow u ONLY to lift 6 reps max? aim for a weight taht allows you to do about 8-10 reps MAX. btw wheres ur cardio lol

sleep. dont go to training tired. get enough rest about 6-8 hrs of sleep per day for an average person, if u can do with less, can also. like darkie said body building = recovery = bodybuilding.. u go into the gym to workout, you bodybuild outside the gym when give ur body what it needs to repair n grow.

keep it simple n always re evaluate yourself, are you doing these 3 right? even if 1 of them isnt done right, your growth can be affected.in terms of gain in muscle mass n fat loss.

remember to check the 'do not combine with previous post' haha.

neways, if u can do pull ups, machine is fine but if u wana get stronger to be able to pull up do negatives. hang from pull up n try to not fall to the floor straight. eventually ull b able to resist more n more n soon ull b able to do 1 rep pull up! keep it up n ull b able to do more.