Check below code to add Button in Toolbar.

If you want to open wizard on Clicking on new added button from Toolbar than first create model and his view file and than use act_window for that view so you can get Button on Toolbar.

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

            <field name="name">Bla Bla Wizard</field>

            <field name="model">wizard.model</field>

            <field name="arch" type="xml">

                <form>

                    <group>

                        <field name="A"/>

                        <field name="B" required="1"/>

                    </group>

                    <footer>

                        <button name="call_method" string="Ok"

                            type="object" class="oe_highlight" />

                        or

                        <button string="Cancel" class="oe_link"

                            special="cancel" />

                    </footer>

                </form>

            </field>

        </record>

<act_window id="action_bla_bla_view" 

name="Bla Bla" 

res_model="wizard.model"

src_model="own.model" 

view_mode="form" 

target="new"

multi="True" 

key2="client_action_multi" />

Hi ,

\

Daniel Lusignan

refer this:

https://supportuae.wordpress.com/2017/09/06/how-to-add-button-in-tree-view-header-near-create-and-import-buttons-odoo10/