This if for a Spanish final in 9th grade.
Ser is used to describe permanent conditions. Estar is used to describe temporary conditions. For example, when you asked someone "Como esta, Usted?," you are asking how they are doing (at the moment). This is subject to change. However, if you state, "Soy de Mexico," that means that you are from Mexico (i.e., you were born in Mexico). That condition cannot change.