I can try to help you out. First of all, no, I don’t think there is a guide out there yet. I’m sure they would love to have one written up!
Basically, you work your way through the levels, learning to code as you go.
The basic difference between the multiplayer and the single player games is that in multiplayer your code will battle against the code of other players. You start by fighting against a very basic AI, once you beat the AI you are allowed to submit your code to the ladder for ranking. At this point simulations are run to pit your code against all the other code and you received a rank. This is where the “Human” and “Ogre” code come in. That is a holdover from the earlier multiplayer levels where you actually had the two different races battling (see http://codecombat.com/play/ladder for these levels, but they are MUCH more difficult than the current campaigns.) Basically if you submit code as a human you battle against any code submitted as ogre. You can submit code for both sides, it may be the exact same code, or you may make do two different strategies.
Hope that helps you out!