To create workflow in openerp use these below step

1. In academy.py file

  import academy.py

2. In __openerp__.py file

 data:["academy.xml", "academy_workflow.xml"],

3. In academy.py file

class session(osv.osv):
    _name="session"
    _columns={
              'state':fields.selection{[
                                        ('draft', 'Draft'), 
                                        ('new', 'New'),
                                        ('confirm', 'Confirm')

                                      ]
                                          'stage', readonly=True,
                                       }
              }

    _def stu_draft(self, cr, uid, ids):
         self.write(cr,uid, ids,{'state':'draft'})
    _def stu_new(self, cr, uid, ids):
         self.write(cr,uid, ids,{'state':'new'})

4. In academy.xml file

  <button name="stu_draft" string="send to new" states="draft", type="wrokflow">
  <button name="stu_new" string="send to confirm" states="new", type="wrokflow">

5. In academy_workflow.xml file

    <openerp>
        <data>
            <record model="workflow" id="wkf_academy">
                    <field name="name">Academy.wkf</field>
                    <field name="osv">session</field>
                    <field name="on_create">True</field>
            </record>
     <!--Workflow Activities-->

         <record model="workflow.activity" id="act_draft">
            <field name="wkf_id" ref="wkf_academy"/>
            <field name="flow_start">True</field>
            <field name="name">Draft</field>
            <field name="kind">function</field>
            <field name="action">stu_draft()</field>
        </record>


        <record model="workflow.activity" id="act_new">
            <field name="wkf_id" ref="wkf_academy" />
            <field name="name">New</field>
            <field name="kind">function</field>
            <field name="action">stu_new()</field>
        </record>
<!--Workflow Transitions-->

        <record model="workflow.transition" id="t1">
            <field name="act_from" ref="act_draft"/>
            <field name="act_to" ref="act_new" />
            <field name="signal">stu_95;new</field>
    </record>

        <record model="workflow.transition" id="t2">
            <field name="act_from" ref="act_new" />
            <field name="act_to" ref="act_assign" />
            <field name="signal">stu_assign</field>
    </record>   

</data>
</openerp>