hihi. if i want to add 2 fields, 1 with dropdown option.. how to do that?

1 with 3 dropdown options for school name ( abc university , def high school, ghi private school)
the 2nd will be student ID.. all numbers no hyphens allowed.

how to add the dropdown field ?
also the student ID, how to add the field + do an error check ? This field is same like the tax field you have added in the first page?

im quite a newbie. please help to give me as detailed instructions as possible. thanks!!