Draw weight is the amount of tension on the string that you will be pulling back (how hard the bow is to pull)

Draw length is the natural "good" position "form" of the draw. There are ways to adjust most all bows so that at full draw you are in good form. A correct draw length should put your pull hand knukles about at your ear. To have the bow fitted to you should be fairly cheep (under 50 over 20 bucks)

go to a bow shop and they will be willing to get you started, bad habbits are hard to break so start off right at the bow shop.