how do they have babys

Question
How do parrots have their babys

Answer
A male mates with the female which fertilizes her eggs internally.  A few days (or several days) later the female lays the egg which is now hard shelled, but has the embryo inside being fed by the large yolk.

As the embryo grows the yolk size decreases.

The mom and quite often, also the dad birds take turns sitting on this and sometimes one or more other eggs in the nest.  They must carefully keep them at a certain temp, gently turning them a little bit now and then so the embryo doesn't 'stick' to a side of the egg inside (which would probably cause it's death).

Depending on the type of bird, about a month after laying (again, some birds are less, some are more) the yolk is used up, the baby is as formed as it will get in the egg and with what's called an "egg tooth" it starts pecking at the egg from the inside to get out.

Baby birds are not "born" they are hatched.  Only mammals (milk fed babies) are born, such as whales and humans, monkeys and hamsters and all the rest of them.
 Baby birds are hatched without eyelids (their eyes are still not fully formed) and they're completely featherless.  In fact, they still look like little fetuses.  

The male and female will often both nurture this baby (and the others if any) by regurgitating food to them regularly and most importantly, keeping them warm.  The babies develop at lightening speed compared to a mammal.  This totally helpless, featherless, blind little chick will be remarkably 'bird' like in just a few weeks!  

They aren't ready to fledge (fly and leave the nest) for a while though.  Once again, depending on the species of bird/parrot, it could be about 6 weeks from hatching or a couple months.

 if you have any other questions about this, let me know or take a look here  www.4AnimalCare.org