You only have one teacher so you can get to know them really well.
You'll probably have more teachers in the first week than in your whole time at primary school.
Each one will have their own rules, some of which will seem really stupid.
You will have a tutor. This is the teacher who takes your register. They will help you to settle in.
If you have a big problem with one of your teachers ask your parents to call your tutor about it.