Finding your way through a new building and learning a new schedule can be a very difficult change, especially if your grade school classes were just in the same few rooms. In high school, almost every class you take will be in a different room. Your schedule can also make things difficult, since there is a very good chance all your classes could be on opposite sides of the school. You will only have a couple minutes to move between classes, so you have to plan locker trips wisely.
Make sure that you know when you can visit your locker and carry all the books you will need for the classes before then so you are not late for your next class. If you get your schedule before the school year begins, it is a good idea to visit your school before the year starts and go through your schedule while the building is empty. On the first few days of school, it is okay if you get a little lost and are late for class. After about a week, you will get used to your new schedule and develop a routine, so I wouldn't be too stressed about navigation.
Make sure that you know when you can visit your locker and carry all the books you will need for the classes before then so you are not late for your next class. If you get your schedule before the school year begins, it is a good idea to visit your school before the year starts and go through your schedule while the building is empty. On the first few days of school, it is okay if you get a little lost and are late for class. After about a week, you will get used to your new schedule and develop a routine, so I wouldn't be too stressed about navigation.