I had no idea, hadn't even held a baby until mine came along. But you kind of pick things up - the practical stuff is surprisingly easy actually, and then they slowly grow up and you find yourself chatting to them, pointing things out, going along to playgroup, chatting to mums about things they do. THen they start showing an interest in things, and so you kind of do those things more.
So, my nearly 2yo DS likes being outside and being active, so we spend a lot of time in the park, at the pool, in the garden and at playgrounds. However, he isn't overly bothered by animals so we don't bother much with the zoo. Other friend's kids love animals so they go off and do animal things.
Mine also likes cooking, so we "make" a lot of food together like crumbles, bread, flapjacks. He also likes books so we read a lot.
As for the early days, as long as you feed them, change nappies, cuddle them, take them outside a bit and give them a bath now and then (we used to do ours about once every 4 days i think) they will be fine.
We had "What to ex[pect the first year" and I thought it was useful although she has loopy ideas re nappies. Nappies are v v simple to change.