[Mayson]

No need to pay anyone for the how-to. I'll explain.
You can call each credit union (Experian, Equifax, TransUnion) to change the address, which will add your drop address to their "current address" field.
OR, a more effective way is to open a bank account/credit line/loan using your drop address. Twice a month, banks/creditors update credit unions with your payment history and addresses, so your new drop address will be added automatically after 15 days of opening your new account/credit line/loan.
Those are the only 2 ways.