School enrollment... HELP!?

okay well first of all i'm going into 7th grade so this has nothing to do with college. all i need to know is how to go into a different school. here's the story : my best friend lives in a different city, and her mom is letting me move in for the school year so i can go to school with my friend. i need to know what MY mom has to do so i can legally go to the school (which is public) for the whole school year. if any of you have knowledge on how to do this, then please help me.(: thanks!