I have a AMD Phenom II X6 1065T and i want to overclock.
what would be the best software program to use to do so?
and would my stock heatsink and fan be good enough to keep it cool?
The stock heatsink will NOT be enough. You will need a big cpu cooler to keep the temps in check. Look at the Noctua D14 and D15 along with the Phanteks and Deep cool cpu heatsinks.
The best software to use is no software at all. You need to overclock via the motherboard bios. If you did not already know this, I suggest researching as much as possible before attempting to overclock. Its not something to just jump into and learn on the way.