How to reset the debugging in insight?

Hi,

I use insight & JLinkGDBServer to debug my code of AT91SAM7S256.
But I do not know how to reset my source code and have it start from
beginning.
When I download the code to my emulator (SAM-ICE), the start position is
always the end of my main function. I do not know how to restart from
0x0000 and how to stop it at my first line of C source code. And how to
set breakpoint.

Thanks

Min Ge