Personally I would recomend starting with a baby ball python. They are pretty darn easy to keep as a pet, and as with any handling is not to much to worry about, they are subtle for the most part. Knowlege to help you learn more as you and the snake grow older is availible in alot of different sources, including the this great web site here!
I would perfer to see you 11 yr old start this way with a captive baby then tring to catch an unknown species of snake on the ranch, not knowing what your tring to catch is poisonous or not could be a bigger mistake then one might think.
Hope this helps a little, more members in here should add to this because the experience here goes way beyond mine concerning different snakes and other reptiles.