You will need to buy a serial cable to flash it, they are around $3-4 us on ebay. I pasted a link to one, there are many to choose from if you do a little searching.
http://www.ebay.com/itm/New-USB-2-0-to-TTL-UART-6PIN-Module-Serial-Converter-CP2102-STC-PRGMR-Free-cable-/310511987503?pt=LH_DefaultDomain_0&hash=item484bf4eb2f