This may help you:

(0, 0,  { values })    link to a new record that needs to be created with the given values dictionary
(1, ID, { values })    update the linked record with id = ID (write *values* on it)
(2, ID)                remove and delete the linked record with id = ID (calls unlink on ID, that will delete the object completely, and the link to it as well)
(3, ID)                cut the link to the linked record with id = ID (delete the relationship between the two objects but does not delete the target object itself)
(4, ID)                link to existing record with id = ID (adds a relationship)
(5)                    unlink all (like using (3,ID) for all linked records)
(6, 0, [IDs])          replace the list of linked IDs (like using (5) then (4,ID) for each ID in the list of IDs)

In your case you need to use (0, 0, { values })

Insert a new record in one2many fields in odoo9.

Code:

@api.multi

def Create_One2many_method(self):

search_var = self.search([('staff_age','=',0)])

search_var.write({

                    'stud_ids': [(0,0, {

                                                'reg_no':4200,

                                                 'stud_email':'anbulove@gmail.com',

                                                   'stud_phone':'9788987689',

})]

})

i want to explain how odoo framework create related table for many2many for exemple we have your model1 where you created "category_id" and the other model2 where you Create the relation with many2many

Now for each models odoo create table in Psql , so for models1 odoo create in Psql table:model1and for the second model Psql create table: Model2 and for the relation many2many Psql create the third his name is table:model1_Model2

so in odoo create this table with underscore and the 2 table Name

In my case, the wizard should add or relate one or more existing records into the "one2many" field of the new record. Then if I'm not wrong, what I must to do is a (1, ID, { values }) with ID = the id of the fresh new record, right?