I runned this soql to find Account with opportunitie with orders  :
 

SELECT
  Name,
  (SELECT
    LastModifiedDate, CreatedDate, StageName,Name
   FROM 
   Opportunities),
   (SELECT
     OrderNumber
    FROM
     Orders)
FROM 
  Account

I found data :

But when i tried to use report in salesforce , i couln't find that opportunities which is related to that account

Does anyone have  an explanation please?

public class EmailManager {
// Public method
public void sendMail(String address, String subject, String body) {
// Create an email message object
Messaging.SingleEmailMessage mail = new    Messaging.SingleEmailMessage();
String[] toAddresses = new String[] {address};
mail.setToAddresses(toAddresses);
mail.setSubject(subject);
mail.setPlainTextBody(body);
// Pass this email message to the built-in sendEmail method
// of the Messaging class
Messaging.SendEmailResult[] results = Messaging.sendEmail( new Messaging.SingleEmailMessage[] { mail });
// Call a helper method to inspect the returned results
inspectResults(results);
}

what are    mail.setToAddresses(toAddresses); 
                 mail.setSubject(subject);
                 mail.setPlainTextBody(body);
  they methord Or what ? 
I am studing apex and find a lot of difficulty in codes.. 
if they are objects then why do we have not declared/initilise them? 

What is the difference between  $A.get() and cmp.get() functions.