BtBee connection problem with arduino software

in Btbee set up step no. 4 i have trubaling to downlod rxtxserial.dll file

ftp://imall.iteadstudio.com/Programmer/IM121112001_Arduino_Wireless_Programmer/rxtxSerial.zip

it dish ply 550-fail to change distonary.
how can i replace arduino rxtxserial.dll file to this btbee serial file