I am not one of the people who will be here to tell you that all breeders are evil, but I will tell you that breeding dogs is hard work, expensive and not always the fairytale you might imagine. That said, I firmly believe that we need good breeders producing healthy litters, and everyone has to start somewhere.
To start with (beyond learning that Labrador Retrievers are yellow, not golden, as PP said), you need to get xrays and official KC/BVA hip and elbow scores done and DNA testing in place for the eye conditions that the breed is prone to. This is not 'just for show people', in case you think it is - it's for any responsible breeder who wants to sell healthy pets too.
Bear in mind that as well as being expensive, getting results from all these tests takes time, so you need to plan well ahead. Obviously, if any of the results are unacceptable, that should be a dead end to the whole process.
Once those are done on your bitch, you need to find a stud dog with all these health tests in place, again with good results, and approach his owner to find out whether they would accept your bitch. If your bitch is not a good example of the breed, they may say 'thanks, but no thanks'.
If all goes well and you have a litter due, then brace yourself for weeks of hard work and worry, with lots of joy scattered amongst it. You will be needing to sleep with your bitch when puppies are nearly due, through to when they are more mobile and can be left without supervision - probably three weeks.
Then you can go back to your own bed, and you'll need your sleep because when they are up and about is when the work really starts LOL. Constant cleaning, washing, feeding, picking up poo, rinse and repeat.
Vetting prospective new owners and meeting them before you agree to sell them a puppy is also a big old hassle, but can lead to life-long friendships. Don't underestimate how what you thought were committed new owners suddenly change their minds too, and if you have a large litter believe me, at 4 months if you are left with several puppies you'll be tearing your hair out. There are a lot of Labradors available for people to buy, and many people won't buy any of them when it comes to the crunch.
Further to this, of course, is that you can end up with huge vet bills for eclampsia, c-sections, puppy issues - or at worst case a dead bitch. Like it or not, this is the reality of any animal reproducing, and it all needs very serious thought. It really is easier just to buy a quality puppy if you want another, unless you are very committed.