What's the correct format to insert a entity with foreign keys in Hibernate?

What's the correct format to insert a entity with foreign keys in Hibernate?

I want to save a row of Penatu in database. I have three entitys.
Have I to create three entitys? or Can I use only a entity object for
setter the other property to save?
@Entity
@Table(name="PE_NATU")
public class PeNatu{
private long peNatuId;
private String apeMat;
private String apePat;
private Persona persona;
..................
@Id
@GeneratedValue(strategy=GenerationType.AUTO)
@Column(name="PE_NATU_ID", unique=true, nullable=false)
public long getPeNatuId() {
return this.peNatuId;
}
etc .....
@Entity
@Table(name="PERSONA")
public class Persona {
private long personaId;
private Set<PeNatu> peNatus;
private TmDocIden tmDocIden;
etc .....
@Entity
@Table(name="TM_DOC_IDEN")
public class TmDocIden{
private String tipoDocId;
private Set<Persona> personas;
etc....
is this correct?
//Class Service- Impl
PeNatu admin=new PeNatu();
admin.setApePat("Test");
admin.setApeMat("Test");
admin.getPersona().setPersonaId(7777)
admin.getPersona().getTmDocIden().setTipoDocId("05");
long idInserted= dao.insertarPeNatu(admin)
Is this correct to get the id inserted,I use oracle DB?
//DAO -Impl
public long insertarPeNatu(PeNatu p) {
Session session = sessionFactory.getCurrentSession();
session.persist(p);
session.flush();
return p.natu.getPeNatuId();
}