How to add text under ''Billing Address"

[jelly]

Concerning the checkout procedure:
How can I add some text under Billing Address, just like there is standard some text under Shipping Address?
(I hope I am clear: I mean under the words Billing Address and above the button COM_VIRTUEMART_USER_FORM_EDIT_BILLTO_LBL )

For shipping address I can use: COM_VIRTUEMART_USER_FORM_EDIT_BILLTO_EXPLAIN
Where can I find this for the Billling Address?

Why? I want to tell the shopvisitor that he has to fill in his Billing address first in order to have the shop properly working. If the shopper starts choosing a shipping method first, not all shipping methods are shown since the shop has to know in which country the person is located (in order to select the proper shipping methods available for this customer).