trouble uploading with uno

I have just bought an uno for Mac with OSX10.4.11. I have downloaded software but keep getting error message when I try to upload sketch -

Binary sketch size: 1010 bytes (of a 32256 byte maximum)
avrdude: stk500_getsync(): not in sync: resp=0x86
avrdude: stk500_recv(): programmer is not responding

anyone able to explain why and how to solve this?

thank you

anyone able to explain why and how to solve this?

The why is simple. The uploader can not communicate with the Arduino. The causes are varied. At the bottom of the error message, it was suggested that you should take a look at the local equivalent of this page: http://arduino.cc/en/Guide/Troubleshooting Getting on the forum asking for help is waaaay down at the bottom of the list.