i need help Arduino mega

when i tying to upload a program to my ARDUINO using arduino sketch i got this message

avrdude: usbdev_open(): did not find any USB device "usb"

what can i do ?

Try a different cable?

Click the menu item Tools then Programmers then Arduino as ISP. Try again.

i tried another USB cable but the same problem occur

i tried this
Click the menu item Tools then Programmers then Arduino as ISP. Try again.

new error message appear:
Binary sketch size: 1,632 bytes (of a 258,048 byte maximum)
avrdude: stk500_getsync(): not in sync: resp=0x00

Did you disable auto-reset?

how can i do (disable auto-rest )??

http://arduino.cc/playground/Main/DisablingAutoResetOnSerialConnection

If you're using standard USB cable and not an AVRISP or arduino ISP programmer, click on the tools menu in the IDE and see that there is a USB serial port listed under "Serial". make sure it is selected.

Also under tools check the "Board" option and make sure you have the correct Mega selected.