i am new in magento i want to redirect customer to "Register" page when customer click on log in button if user email address and password is not match
You can override this method:
Mage_Customer_AccountController::loginPostAction and in
case Mage_Customer_Model_Customer::EXCEPTION_INVALID_EMAIL_OR_PASSWORD just redirect to
$this->getUrl('customer/register'), but I don't recommend it. Sometimes users fill in a wrong password and it becomes annoying to have to click again on the login link.