Gravel
Mr. Poopybutthole
You technically can jump right into normal matches if you want (can't start ranked until you hit some arbitrary account level though).So, I'm starting this game.
Are you supposed to beat the BOT tutorial game with Dragon knight?
I'd say run a couple bot matches (solo if you've never played a MOBA, coop if you have) before jumping into normal games. That said, I think Dota is unique as far as mechanics that other MOBA's don't have (denying creeps/towers, tower aggro, etc). I think the tutorials touch on those a little bit, but your time might be better spent either having someone from here tell you (Rethan helped me a great deal with this when I started, as did Intrinsic), or watching Youtube videos.