How to unlock to overclock

I'm trying to overclock my computer using the AMD Overdrive program. I've already tried to do it in the bios. (But I couldn't get the area to highlight so as to make any changes). I'm having the same problem in the AMD overclock program. I have an AMD Phenom 9550 (Code name Agena)Quad core processor with a AM2+ Socket (940) Core speed now is:2200.2 Mhz, FID is 11.0x,and my HT link speed is 1800.1Mhz, the VID is 1.250V. any ideas?