What,Why and How to spay a bitch?

Question
I have a labrador retriever. i wanna know about spaying a bich in brief!
Please help!!

Answer
For all but serious breeding programs or show dogs, it is best done by 6 months.  That usually is soon enough to avoid having to go through the mess, hassles, and risks of having one go through its reproductive cycle.  Early spaying may result in some minor structural differences, but even if so, it is minor and much less concern than the problems of keeping an intact female.  

Spaying requires surgery and must be done by a vet.

It has many advantages, mostly avoiding the problems with reproductive cycle, heat.  The cycle starts with behavior changes, then the vulva swells, followed by a bloody discharge lasting a few weeks.  The second and third weeks are when the most risk of accidental breeding is. Don't take this lightly. She will do anything to get loose and get to a male. Once loose, an accidental breeding and an unwanted litter is far from the worst that can happen. Such breedings can also result in fatal infections. She can get killed when she dashes heedlessly across the road in front of a car. Other dogs or wild animals may kill her.  Longer range, spaying reduces the chances of cancer and other things life threatening and expensive to treat.  It also reduces aggressiveness and makes the dog easier to manage.