lifting weights...need help..want to left more..max 150...what should i do to li!

You do a warmup set to get the blood flowing. Then you start out heavy even if you cant do more than 3 reps. then you drop a little weight off and do it again. once again after that. and you should only work one body part once or twice a week. You tore your muscle fibers and for it to grow and be stronger they need to recover. Also you should be eating your body weight maybe more of protein a day for your muscles to recover faster and to grow. The heavier the weight the stronger you get and more mass you gain. It doesnt matter if you can do all 3 sets with 10 reps. you want strength so lift heavy even if its one good rep and and let your muscles recover. the next time you lift it will be easier and you can probably add weight.