HOW TO... HIRE A STEWARD
The help with the running of your new homestead you can recruit a follower to become your steward, who will then move in and carry out a number of tasks for you. Only certain followers can take on this role, but this includes any of the housecarls you receive for becoming Thane of a hold and many of the quest-based followers.
Once you have an appropriate follower, return to your home and upon arrival they will offer to take on the role of steward - accept and they will stop following you then move into your house.
A steward can obtain a carriage to transport you around, a bard to provide musical accompaniment to your daily life, a horse for your stable and cows and chickens for your animal pen. They can buy building materials for you, saving you a trip to the lumber mill for sawn logs, but don't forget that clay and quarried stone can be sourced for free from the area surrounding your house. You can also instruct them to buy furnishings for rooms, saving you the hassle of constructing all the individual items yourself.
HOW TO... START A FAMILY
With your home fully constructed, you can now turn your attentions to the other new feature of Hearthfire, adoption. You don't need to be married to open up this option, but you do need to have installed at least one child's bed and one container (such as a dresser or wardrobe) in the child's bedroom before your house will be deemed suitable. You also need to have completed the quest "Innocence Lost" to kill Grelod the Kind before adoption is available to you.
With you home prepared accordingly, head to the Honorhall Orphanage in Riften and speak to Constance Michel then offer to adopt one of the children. She will ask you a series of questions to check your suitability, tell her you're the Dragonborn and where your house is located. Once accepted you can speak to the children and choose one to adopt, who will then be transported back to your house.
You can adopt a maximum of two children, either from the orphanage itself or from stray orphans found wandering around the major cities.
HOW TO... ENTERTAIN YOUR KIDS
Once your child has moved in, you need to keep them happy. New items are available to purchase from merchants such as clothes, wooden swords and dolls, which can be given to them in addition to traditional items such as sweet treats.
You can play games with your child such as hide-and-seek and tag, and if you have two children they will both join in the fun. If you catch your children arguing with each other you can step in and scold them, you can also send them off at any point to do chores.
Sometimes your child will return home with an animal and ask if they can keep it. If you agree, the animal will become their pet and live with you in the house.