You get 1 science for 1 population, so you either want a couple of massive cities, the consensus usually being around 4 without having to suffer through physical depression, or tons of small cities, although economically, you'll have trouble maintaining all those libraries, universities, public schools (generally, good cities pay for themselves). Increase food by farming plains and grasslands, build granaries, settle cities next to rivers and build a water mill, go for the Hanging Gardens in your Capital early on. To get the most out of your science, try to get to education as soon as possible, build the Porcelain Tower to get the most out of your RA's. Honorius mentioned everything else.
You can use Babylon in multiplayer, but only if the DLC is checked, and all others aren't (assuming you don't have the other ones).
Let me guess, you got the $20 steam deal with the free Babylon civ right? Welcome to the club.