Retrieve data using Ajax.request

Where will i place the Ajax.request codes?

Code:

---

Ext.Ajax.request({
  url: 'http://www.mydomain.com/WebService/MyRequest',
  method: 'GET',
               
  callback: function(options, success, response) {
        console.log(response.responseText);
  }
 });

---

What do you mean?