Hello Lince,

You can add new column in the any tables using inherit.

For Ex :-

In py

class Users(models.Model):

     _inherit = 'res.users'

     first_name = fields.Char('First Name')

In Xml

<record id="res_users_form_view_inherit" model="ir.ui.view">

    <field name="name">res.users.form.view.inherit</field>

    <field name="model">res.users</field>

    <field name="inherit_id" ref="base.view_users_form"/>

    <field name="arch" type="xml">

        <xpath expr="/form/sheet/div[@class='oe_title']/group/field[@name='partner_id']" position="after">

            <field name="first_name"/>

        </xpath>

    </field>

</record>

Now First name is display after Related Partner in Users form view.

For Contact, You will inherit res.partner model.

Hope it will works for you.

Thanks,

There is already a module available in the App store for this purpose: https://www.odoo.com/apps/modules/9.0/partner_firstname/     

You should be careful to not break a lot of things if you do not ensure that the regular field "name" still has the proper value.

Note: i am assuming that you are not a developer.

For Adding a new field in any  model follow these steps:

1. Go to setting-> technical->Database Structure ->Fields 

2. Click on Create

3. Put the Field Name(x_first_name),Model(Users) ,Label/String[First Name] , Type[Text] etc.

4. Save it.

Now open the corresponding  view in edit mode ,put your field like  <field name = "x_first_name"/> and save.