Search the web for disassembly or cleaning guides. CPU overheating in laptops is frequent and perfectly normal because of dust buildup on the heatsink.
Try one of this guides:
https://www.ifixit.com/Device/Alienware_M14xR2
They are for replacing parts but should give you an idea how to open your laptop to a point where you can clean it.
Attention: laptop disassembly will void any warranty, if you still have any. Also it's not the easiest thing to do, so unless you have some experience, better ask a friend or take it to repair shop.
Edit:
here's an even better one:
http://www.instructables.com/id/Alienware-14-Disassemble-Instruction/