Since Rosh Hashanah is the Jewish New Year, it is technically more "proper" to wish someone a happy new year, or "Shanah Tovah," which means "good year" in Hebrew. That being said, when anyone extends a greeting to a Jewish person wishing them well on a sacred Jewish holiday, it is extremely meaningful, even if the words aren't perfect! So don't worry if you don't get the words exactly right - just know that your heart-felt wishes mean a lot to those celebrating.