creating trigger in salesforce

1) Create an Apex Class

  Steps:   Click Your Name | Setup | Develop | Apex Classes and click New. 

  Paste the following code there.

 global class asyncApex {

  @future (callout=true)
  public static void processAccount(Id accountId) {
  
  sObject s = [SELECT Id, Name FROM Account WHERE Id = :accountId LIMIT 1];
  
// Instantiate a new http object
    Http h = new Http();

// Instantiate a new HTTP request, specify the method (GET) as well as the endpoint
    HttpRequest req = new HttpRequest();
    // this is a test url
    req.setEndpoint('https://evening-lowlands-4200.herokuapp.com/tt?id='+s.Id+'&name='+s.get('Name'));
    req.setMethod('GET');

// Send the request, and return a response
    HttpResponse res = h.send(req);
    System.debug('hiii');
    System.debug(res.getBody());
    //return res.getBody();   
  }   
}


2) Create an apex trigger that trigger the web service in the apex class
  
  Steps: click Your Name | Setup | Customize, click the name of the object, then click Triggers and click New.

  Paste the following code there.

  trigger accountAsyncTrigger on Account (after insert, after update) {
    for(Account a: Trigger.new){
      asyncApex.processAccount(a.id);
    }
  }