When your dog comes home from her spay surgery, she needs peace and quiet and limited activity for about two weeks. That's easier said than done. Young, active dogs aren't aware they've had major abdominal surgery, so it's likely she'll want to run and play a couple of days after the operation. It's your task to ensure she recuperates safely and doesn't engage in behavior that could open her incision.
If her surgery went well, she'll probably come home the same evening. Provide a quiet place in your house for her to recover, outside of the home's main traffic areas and away from other pets or kids. She needs to rest. Expect grogginess for the next day or so as the anesthetic wears off. Your vet will prescribe medication for pain relief. As per your veterinarian's instructions, you can give your dog small amounts of food a few hours after she returns home. Your dog should always have water available. She can probably consume her normal diet in a day or so.
The Cone of Shame
Your vet will probably give you an Elizabethan collar -- the infamous "cone of shame" -- to put on your dog while she recuperates. Yes, your dog will hate it and her eyes will implore you to take it off. Don't give in. This collar prevents her from licking or gnawing at her incision, possibly opening it up. She'll probably need to wear the collar for at least a week. If the incision swells, appears inflamed or opens, call your veterinarian immediately.
Take your dog out for potty breaks on a leash, even if you have a fenced-in yard. Don't let her loose into a yard or pen to relieve herself, because she might start running around. For the first week following surgery, restrict her activities. That means no rough play, long walks or outings with other canines. She shouldn't have a bath or otherwise get wet for a week after surgery.
Back to Normal
If her incision heals well and she seems fine otherwise, your dog can resume her normal activities two weeks after her spay. She might appear perfectly normal just a few days after her surgery, but that doesn't mean she's fine. The sort of surgery that knocks humans for a loop for weeks often doesn't faze a dog. Just give her two weeks of loving care while she's recuperating and you'll be rewarded with years of loving companionship with no fear of pregnancy.