At 303lbs (assuming you are obese) you don't have to worry much about the details of weight lifting. You need to go to a gym and learn how to lift weights safely. Get your food intake sorted out and make sure you have a protein shake after each workout.
log your weight every week and as long as you are eating properly the weight will come off over time. Your weight will vary a lot due to water retention, stomach contents, etc so don't get too upset about gaining/loosing in the very short term. If you don't loose after a couple of weeks look at your food intake again.
save the planet - it's the only one with chocolate