(OneToMany relation)how to save the date through Mapping in java

hey,, i am mapped(onetomany relation) the java file ,,
i have done map a file and also generate the table in sql,, but i cant save a value in mapped file,,,,,, i doing map a file class and section.. if user select the class then display the section according to class ..

how to save the class and section in mapped file ..

please tell me a one example how to save a mapped file record and display a console..

ya tell me a method and action

how to save a value of a record or display the value in mapped sql table