Before you even think about overclocking, be a real good idea to know exactly what components you actually have. Based on what you have listed in your specs, you need to figure that out first. If it is still the original HP motherboard that you have in it then you can outright forget about overclocking as the bios will be locked from being able to do so.
If it isn't the HP motherboard, fill in the exact make and model of motherboard you do have. Also here is another guide to help, AMD Overclocking Guide - Guru3D.com Forums
As for what can go wrong; the wrong settings can either cause it to be unstable in windows and BSOD, or it can just outright refure to boot at all. If it BSOD's you need to back off on your settings. If it won't boot after making changes, then you need to check the motherboard manual on how to reset the bios; either by jumper or if supported, holding the power button for a few seconds.