if the processor is locked then the bios wont allow you to unlock it. but from what i gather that cpu can be oc'd a little so my guess its your bios has locked it rather than amd. in this case you need to figure out how to unlock it. often them features are on an advanced hidden menu. try pressing shift F1 or F1 while in bios on the cpu menu it may open another menu like MIT or some such.
you can increase the ht speed and get more from it that way but really you want to unlock the multiplyers for the clock freq and NB so you can oc it properly without boosting the whole board.
dont oc if you only have stock cooling. you will kill your cpu quicker than you can blink as the stck parts are built with very small tolerances and wont be able to cope with the extra heat created by the oc..