How can I add the standard header with "create button"(and in form view the standard save button) and search field to my module like in the image?

I creaded a module with a new model/object, tree and form view. but the tree view and the form view don't shows the header with the "create button"...

my xml:

<openerp>
<data>

    <record id="background_task_form" model="ir.ui.view">
        <field name="name">background.task.form</field>
        <field name="model">background.task</field>
        <field eval="7" name="priority"/>
        <field name="arch" type="xml">
            <form string="Background Tasks" version="7.0">
                <header>
                    <button name="start" string="Start" type="object"/>
                </header>
                <sheet>
                    <h1>
                        <label string="Background Tasks"/>
                        <field name="id" class="oe_inline" readonly="1"/>
                    </h1>
                    <group>
                        <group>
                            <field name="model"/>
                            <field name="method"/>
                            <field name="arguments"/>
                            <field name="user_id"/>
                            <field name="priority"/>
                            <field name="status"/>
                            <field name="max_time"/>
                        </group>
                    </group>
                </sheet>
            </form>
        </field>
    </record>

    <record id="background_task_tree" model="ir.ui.view">
        <field name="name">background.task.tree</field>
        <field name="model">background.task</field>
        <field eval="7" name="priority"/>
        <field name="arch" type="xml">

            <tree string="Background Tasks">
                <field name="id"/>
                <field name="model"/>
                <field name="method"/>
                <field name="arguments"/>
                <field name="user_id"/>
                <field name="priority"/>
                <field name="status"/>
                <field name="max_time"/>
            </tree>

        </field>
    </record>

    <record id="background_task_filter" model="ir.ui.view">
        <field name="name">background.task.select</field>
        <field name="model">background.task</field>
        <field name="arch" type="xml">
            <search string="Search Background Tasks">
                <field name="model" string="Background Task Model" filter_domain="['|',('model','ilike',self)]"/>
           </search>
        </field>
    </record>

    <record id="action_background_task" model="ir.actions.act_window">
        <field name="name">Background Tasks</field>
        <!--<field name="type">ir.actions.act_window</field>-->
        <field name="res_model">background.task</field>
        <field name="view_type">form</field>
        <field name="view_mode">tree,form</field>
        <field name="domain">[]</field>
        <field name="search_view_id" ref="background_task_filter"/>
        <field name="help" type="html">
          <p class="oe_view_nocontent_create">
            Click to create a quotation that can be converted into a sales
            order.
          </p><p>
            OpenERP will help you efficiently handle the complete sales flow:
            quotation, sales order, delivery, invoicing and payment.
          </p>
        </field>
    </record>
    <menuitem action="action_background_task" id="menu_background_task" parent="base.menu_config" sequence="16"/>


</data>
</openerp>

my py:

from openerp.osv import fields, osv


class background_task(osv.osv):
    _name = 'background.task'

    _columns = {
        'model': fields.char('Model Name', size=64, help='E.g. "product.category"', required=True),
        'method': fields.char('Method', size=64, help='Method to be called from model.', required=True),
        'arguments': fields.text('Arguments', help='Arguments that will be passed to method.'),
        'user_id': fields.many2one('res.users', 'User', required=True),
        'priority': fields.integer('Priority', help='Higher will be processed first.'),
        'status': fields.char('Current status'),
        'max_time': fields.integer('Max execution time', help='Max execution time in seconds.'),
        'cron_id': fields.integer('Cron ID', readonly=True),
    }

    _defaults = {
        'priority': 100,
        'status': 'new',
        'max_time': 300,
    }

    _order = 'priority DESC, id'

background_task()