How to properly resign?

So I’ve never resigned after putting in my intent to return. I was offered a job the other day and am needing to send a resignation email. I have a few days to send it. I want to resign on decent terms. I’m unsure who to email other than the building principal. Should I text the principal first to thank them and explain my reason for leaving and then still send a formal email? I have no idea how to go about this. In the resignation email, do I mention what district I’ll be going to? Any tips are appreciated!