You all want to know how people and animals are born since that is what it's called when you make people and animals. This is a good question for a parent and we think you should ask them too. But we will give you an answer since you have been patiently waiting for IO to ask a scientist.
young scientist in room 3, has done some research and provided us with this answer. She had this to say about being born. She wrote it about people, but the answer is the same for many animals, cats and dogs for sure.
The baby grows in an organ in the mother called the uterus. After about 9 months (could be quite different for some animals), the baby is ready to be born. Labor begins. Labor is when powerful muscles push the baby out through a tube and out of the vagina. The tube is usually only 1/4 of an inch wide. Out comes the baby. You were born!
There are some books in your school library about this subject.