1.) you can use an FTDI cable... (purchased)
2.) you can MAKE an 'FTDI cable' from a cell phone data cable.. (although I have found these do NOT have a reset/dtr wire....but you have a reset button on your standalone so it doesnt matter)
3.) you can take your Real Arduino... pop out the Atmega 328 DIP chip... and wire your stand alone circuit up to the board with no chip
Arduino >>> Standalone
RESET >>> DTR
RX >>> RX
TX >>> TX
GND >>> GND
5v+ >>> 5v+
if you have NOT included a DTR set-up with cap...on your standalone board.. you will have to either add that.. or.. hit the reset button, and time it correctly whenever you want to upload a sketch..
example.. (after everything is wired up)..
you open IDE.. set COM PORT.. set BOARD type..
open sketch.. hit upload.. when you see the sketch size text show up at bottom.. I iut reset button quickly..
(this resets the bootloader, so it will look/accept any incoming sketches)