How to Genrate XMl Formated Data for return in web service

Hello,

I have an issue to select and data to see element and return it back to be consumed in web service. bellow is the format to return the data.

<CustomerInformationResponse>

 <MerchantReference>639</MerchantReference>   

 <Customers>

       <Customer>           

 <Status>0</Status>            

<CustReference>23470</CustReference>

<CustomerReferenceAlternate> </CustomerReferenceAlternate>

             <FirstName>test test</FirstName>           

 <LastName> </LastName>          

<Email>tester@gmail.com</Email>           

 <Phone> </Phone>             

<ThirdPartyCode> </ThirdPartyCode>            

<Amount>234078</Amount>            

<PaymentItems>                

<Item>    

 <ProductName>PayAtBank</ProductName>                  

 <ProductCode>01</ProductCode>                    

<Quantity>1</Quantity>                    

<Price>234078</Price>                    

<Subtotal>234078</Subtotal>                   

 <Tax>0</Tax>       

             <Total>234078</Total>  

              </Item>            

</PaymentItems>       

 </Customer>     

</Customers>

</CustomerInformationResponse>

Please can any one help me on how to get this done ?