Although Nelson recommends cooling pads but then goes against them I must disagree. I used to own the world's hottest laptop that would constantly straight shut down when it gets too hot. On the left of the mouse pad it was black because of all the heat. IF you find a cooling pad, that has fan placement exactly the same as where your laptop's vents are, you'll have a much better experience. I managed to find a fanned pad once that was exactly like that and it'd keep my laptop quite cold.
The next thing you REALLY need to do is either pay for someone or find a video on youtube - how to clean your laptop. It really needs to be done quite frequently. Some people recommend every 6-12 months. There will be a lot of dust and gunk blocking all the air ways if the laptop has never been cleaned before. I'd take this opportunity to also change the CPU and GPU's thermal paste (they are very inexpensive).
Cleaning it will make all the difference in the world.
P.P. (As it's an HP and those are horrible to open, I do recommend you take it to a hardware shop, they don't usually charge alot, I had to take my old HP literally apart to clean the dust properly, ever part had to be unscrewed ...)