Nope, sperm going "in a girl's butt" will not make her pregnant.
In short, anal sex will never result in pregnancy.
This is basic biology, and I'm slightly surprised that you genuinely didn't know this was the case.
What I would suggest is that you spend some time learning more about exactly how women get pregnant, and the process of how sperm fertilizes eggs.
This is especially important if you plan to be sexually active in your lifetime.
You may want to check out this video as a place to start:
If you'd like to learn more, I'd recommend asking about sex education courses in your area. These are often provided by education providers such as schools, but your family doctor or your local health service can also shed some light on any questions you may have.
