How to dominate bots: 1) pick blitzcrank 2) at the start of the game, grab a mana crystal and immediately run into enemy base via jungle, eating inhib turret hits 3) grab bots from the fountain and kill them as they stand there, unable to hit back because their AI is set to immobile 4) get free kills till you run out of mana. suicide on fountain turret to get back to base. 5) buy free items. If this isnt enough to let you snowball, stand under your turret and grab punch more bots.
edit: ghost and flashing over the wall into the base if you really think you'd die to the inhib turret.
Lakinnnn, it's like this bud. Bot games don't do anything at all to teach you the game or even teach you any strategy I recommend to play PvP and at the very least Dominion since it's a bit more forgiving imo. You will always be paired against people your level so no worries getting paired against a lvl 30. I would only....I mean only recommend doing a bot game if only for giving a shot at a brand new champion a game or two to get their mechanics down (i.e. learning when to last hit due to their AA animation or practicing their skill shots like Dianas) So if you have a champ you've been playing and enjoy go out there and play PvP. You will die....a lot...no matter what, there is no way you will ever run into a PvP match as a new player and not die close to 10 times or more until you play more and more PvP unless you are one of those anoyyingly lucky new guys.
TL;DR version: Go play PvP right now, quit botting, you learn nothing plus playing badly now at your level is more forgiving than if you wait till you are 15+ to start PvPing.
Since you're going for a support role (Janna is a support character) your CS and kills are supposed to be low. You're there to help out the carry in bottom lane and make sure they get as much money as possible. That being said, you are still learning so don't pressure yourself into a role to harshly, maybe you'll learn you prefer to play a carry or a tank or something.
Reading guides for specific champions helps a lot too.