All of this. You wouldn't modify a car before you knew how it worked, don't make the same mistake with your body.
There are plenty of experienced guys on this site who will happily help you if you come into this with the right attitude. There's a few examples of how to do it right and wrong in the Beginners section right now. My personal opinion would be that you should be looking to lose some of the weight and get a good strength base before you worry about bodybuilding