Download Speccy to check your temperatures or check in the BIOS, core temp has be found to show invalid results (at least for me), also as long as the temperatures stay below 85c at any load you're fine.
At idle on the stock cooler you should be getting anywhere between 30C to 45C depending on where you live and ambient temperatures in the room where the computer is.
You can either get an after-market CPU cooler (which will replace your stock CPU cooler) or you can add additional case fans to your build to decrease your temperatures.