My main computer is an hp zv5000 - it uses two heat pipes with heat sinks and two fans to cool the processor. Through use, those heat sinks (copper?) and pipes collect quite a bit of dust reducing the machine's cooling capacity.
If you don't have this specific machine, not to worry. Just use some common sense as the basic idea is the same.
Step 1: Tools and Supplies and First Step
You'll need two things:
Q tips and a screw driver
First Remove your battery (possibly a duh! step, but just being thorough).
Unscrew the Ram cover - to make removing the rest of the case easier.
You'll need to remove the plastic cover just behind the battery 'cave' - remove any required screws and keep track of where they came from (some of mine were longer than average).