I'm looking to overclock my processor and my graphics card but i don't know how.
And i would also like to know if my Antec Nine hundred Two V3 case will handle it with all but one fans installed (the one on the side is missing). And i have a Cooler Master Hyper TX3 CPU Cooler. And is it worth the risk?
If your heatsink is working nicely and your temperatures are already good, overclocking probably won't hurt anything. The 2500k can easily hit 4.0 GHZ without a major temperature increase, all through just changing the multiplier.
Flashing the GPU... eeeh. Double check to make sure your 6950 is one of the revisions that will flash and not brick when turned into a 6970.