Help welcoming new Jewish staff member

I need help welcoming a new Jewish staff member to my school. I am her mentor for this school year. I live in an area where her family may be the only Jewish family in the entire county. I know Rosh Hashanah is coming up next week, and I’d like to do something nice for her to welcome her to the our community. But I know next to nothing about Jewish culture, and I don’t want to do anything that would offend her. I thought about something small like just a Rosh Hashanah card, but I didn’t know if that was a thing. Does anyone have any suggestions?

Also does anyone have suggestions for a book/website that could help guide me in general? I know I can Google it but it makes me leery because I don’t know what’s actually legit.