If you wanted to call a wizard from button you need to write a button like

<button name='%(module_name.window_action)d' type='action' string='Button'/>

and if you have wrote a method in py file then you need to return action like

def your_method(self, cr, uid, ids, context=None):
    .....
    your code
    .....
    return {
       'name': 'Wizard name'
       'type': 'ir.actions.act_window',
       'res_model': 'wizard_model',
       'view_mode': 'form',
       'view_type': 'form',
       'target': 'new',
       'context': context,
    }

In return "target: new" will popup a wizard. This will help you to call a wizard from another module.