Hello 

you can add button and write method on that button.

Thanks 

In this tutorial you will learn how to create workflow in odoo. Before jumping into the code you need to know about workflow and why we need it.

Odoo workflow

In simple words workflow is "Perform some action in a organized way". To organize tasks or activities we use workflow. In the term of Computer Science workflow is same as the directed graph, where the nodes are called activities and arcs are called transitions. Here activities are some action that could be done on odoo server such as changing the state of some records based on some condition. We can say that the behaviour of the workflow depends on user action (for example clicking on a button).

How to create you own workflow : http://learnopenerp.blogspot.com/2017/12/odoo-workflow.html

Workflows are no longer supported in the Odoo 10.

Hence achieve your requirement, using the standard Button of type "object".