You can legally send a handgun to another state but you have to send it to an FFL in the other state. They usually want you to include a copy of your drivers licence. You should have the FFL FAX or send you a copy of his FFL and the address on the FFL is where you send it. Call the FFL to make sure he is willing to accept it from a private individual, most will. You cannot use the US Postal Service, you must send it by UPS or FedEx. It's usually easier to tell UPS or FedEx it is something else otherwise they want you to send it overnight which is expensive.