I'm trying to create a wizard, but I'm confused about how a wizard works.

This is mymodule.py:

# -*- encoding: utf-8 -*-
from openerp import models, fields

class mymodule_attivita(models.Model):
        _name = 'mymodule.tbl_attivita'
        _description = 'Tabella Attivita'

        scode_attivita_contr =  fields.Char('Code', size=1, required=True)
        sdescrizione = fields.Text('Descrizione', equired=True)

and this is mymodule_view.xml:

<?xml version="1.0" encoding="utf-8"?>
<openerp>
	<data>
		<record id="view_mymodule_attivita" model="ir.ui.view"> 
    		<field name="name">mymodule view</field>
    		<field name="model">mymodule.tbl_attivita</field>
    		<field name="arch" type="xml">
        		<form string="mymodule Attivita">
        			<sheet>
        				<notebook>
        					<page string="Tab 1">
		        				<group name="top">
		        					<group name="left">
		        						<field name="scode_attivita_contr"/>
		        						<field name="sdescrizione"/>
		        					</group>
		        				</group>
		        			</page>
		        			<page string="Tab 2">
		        				<group name="top">
								<group name="left">
									<field name="id" attrs="{'invisible': [('write_date', '=', False)]}"/>
									<field name="write_date" attrs="{'invisible': [('write_date', '=', False)]}"/> 										
								</group>
							</group>
						</page>
					</notebook>
				</sheet>
		        </form>
		    </field>
		</record>
                <act_window id="action_bridge_attivita" name="Attivita" res_model="mymodule.tbl_attivita" view_mode="tree,form" />
                <menuitem id="menu_mymodule_attivita" name="Menu mymodule Attivita" parent="mail.mail_feeds" sequence="20" action="action_mymodule_attivita" />
 
    </data>
</openerp> 

So, I have a form with 2 fields (plus id and write_date that I've set invisible).

I would like to create a wizard to open a page with a button Pushing this button, Odoo has to open the model 'mymodule.tbl_attivita'. So, I've written this wizard.py file:

# -*- encoding: utf-8 -*-
from openerp import models, api

class wizard(models.TransientModel):
        _name = 'mymodule.wizard'
        _description = "Wizard

        @api.multi
        def crea_attivita(self):
            return {
                'type': 'ir.actions.act_window',
                'res_model': 'mymodule.tbl_attivita',
                'view_type': 'form',
                'view_mode': 'form',
                'target': 'new',
            }

with this wizard_view.xml:

<?xml version="1.0" encoding="utf-8"?>
<openerp>
	<data>
		<record id="view_mymodule_wizard_form" model="ir.ui.view"> 
    		<field name="name">Wizard</field>
    		<field name="model">mymodule.wizard</field>
    		<field name="arch" type="xml">
        		<form string="mymodule Wizard">
        			<sheet>
        				<group name="top">
        					<group name="left">
        						<h1>Demo Wizard</h1>
        					</group>
						<group name="right">
							<button type="object"
				                    		name="crea_attivita"
				                    		string="Create Attivita"/>
                                                </group>
                                        </group>
                                </sheet>

				<footer>
					<button string="cancella" special="cancel"/>
				</footer>
		        </form>
		    </field>
		</record>

		<record id="view_mymodule_wizard" model="ir.actions.act_window">
		
			<field name="name">Select link</field>
			<field name="type">ir.actions.act_window</field>
            		<field name="res_model">mymodule.wizard</field>
            		<field name="view_type">form</field>
            		<field name="view_mode">form</field>
            		<field name="target">new</field>
		</record>
  
		<act_window id="action_mymodule_wizard" name="Attivita" res_model="mymodule.wizard" view_mode="tree,form" /> 
	  	<menuitem id="menu_mymodule_wizard" name="Menu mymodule Wizard" parent="mail.mail_feeds" sequence="40" action="action_mymodule_wizard" />
	  	
	</data>
</openerp>  

In this way, I have a link 'Attivita' in the 'Messaging' menu. When I click on it, I open the wizard and I could click on 'Create' and then I could click on the button 'Create Attivita'. At this point, I have a pop up with the field of the model mymodule.tbl_attivita, without the option for saving my data.

I think that there is something about wizard that I haven't understood. Could anyone explain me what is missing?