Have a Baby
To have a baby, obviously you need a male and a female sim. They need to live together (be married) and be practically loving each other (relation bar is at 100.) Then have your sims kiss (eg. 'Fiery' or 'Romantic' or it won't work) and one of the sims will ask 'Shall we have a baby?' If you say yes a cot will appear next to your sims.
Another way to get a baby is if the adoption company ring up and ask if you want to adopt a baby, but this rarely happens.
Look after the baby
When the baby starts crying, it is either hungry or can't get to sleep. There is the exception that it could just be bored. Feed the baby, then sing to it, and if that doesn't work, play with the baby. When the baby is asleep, you cannot interact with it.
If you leave the baby crying, a note will come up telling you that you need to give it attention. if you ignore this too, a social worker will come and take the baby.
You cannot leave the house when there is a baby, but the baby wil grow into a child after three sim days.
Children are even more of a handful than a baby to look after. They cannot get their own meals (they can only have a snack) and you have to get them to go to school every day. If they miss the bus, and they are in a good mood, they may decide to walk to school on their own, but if they are not then the school will ring up to complain and you can scold your children.
They can study to get good grades by using the computer or a bookshelf. If they get an A+, they might even get a reward from Grandad. The school bus arrives at 8:00 every morning.
You need to use 'serve meal' when you have children because otherwise they will only be able to eat snacks, and that will end up costing a lot mre than giving them a meal.
Children never grow into Adult sims so think before you get a child because you'll be stuck with them forever.