Discount Not adding and source chnage

Hi,

How can i change the source option comes under customer tab?

I am trying to add discount to customer but it is not adding, can some check my code and tell whether it is correct or not.

$customer->Name='A';
$customer->Email='test@test.com';
$customer->Address1='House';
$customer->Address2='Street';
$customer->Address3='Preston';
$customer->Address4='Lans';
$customer->Postcode='pr23hj';
$customer->Telephone='0000000';
$customer->Discount='2.5';
$customer->ShowDiscount=1;